A three-machine virtual synchronous generator frequency coordination control method and system

Abstract

The present application relates to the field of new energy technology, in particular to a three-machine virtual synchronous generator frequency coordination control method and system, the method comprises: obtaining the control data of each VSG in the three-machine VSG island system; real-time calculation of the frequency deviation coupling term between multiple machines, generating a virtual dynamic mutual damping torque compensation; combined with the rolling optimization characteristics of MPC control, taking the reasonable interval of frequency convergence to the rated value as the target, building a multi-objective cost function, outputting the optimized active reference power; through the synergistic effect of virtual dynamic mutual damping and MPC, the frequency coordination control is realized. The present application solves the problems of serious frequency deviation, excessive transient fluctuation and poor multi-machine synchronization of three-machine VSG system, not only enhances the frequency disturbance rejection ability of multi-machine system, but also realizes the precise control of frequency, improves the operation stability, synchronization and economy of three-machine VSG island system.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, and in particular to a method and system for frequency coordination control of a three-machine virtual synchronous generator. Background Technology

[0002] Renewable energy sources, such as wind and solar, are being integrated into the power grid on a large scale. Microgrids, as one of the interfaces between distributed generation (DG) and the main grid, are a current research hotspot. When microgrids operate off-grid, their voltage and frequency are easily unstable due to disturbances due to the lack of necessary inertia. Therefore, by introducing swing equations into the converter to simulate the transient characteristics of a synchronous generator (SG), the control of a virtual synchronous generator (VSG), which gives distributed generation systems inertial and damping characteristics, has emerged as a promising approach.

[0003] VSG control has the ability to autonomously construct voltage and actively support the power grid, which can significantly improve the stability of microgrids. However, when the converter simulates SG, the oscillation characteristics of the synchronous motor rotor are inevitably introduced. Therefore, in parallel systems containing multiple virtual synchronous motors, sudden load changes often cause power frequency oscillations in the system, and in some cases, one VSG may bear most of the load, which can easily damage the system's power electronic equipment and ultimately lead to system instability and safety hazards.

[0004] In summary, there is an urgent need for a frequency coordination control method and system for three virtual synchronous generators to solve the problem of uneven load distribution in multi-machine VSG systems. Summary of the Invention

[0005] The purpose of this invention is to provide a frequency coordination control method and system for three virtual synchronous generators (VSGs). Based on a frequency coordination control strategy for three-generator VSGs using virtual dynamic mutual damping and MPC (Model Predictive Control), the method achieves frequency deviation coupling compensation for multiple generators through virtual dynamic mutual damping. Combined with the rolling optimization characteristics of MPC, the active power reference of the three-generator VSGs is dynamically coordinated. This not only achieves accurate convergence of the system frequency but also suppresses transient fluctuations and frequency deviations of multiple generators, thereby improving the adaptability of the three-generator VSG islanded system to sudden load changes.

[0006] This invention provides a frequency coordination control method and system for a three-machine virtual synchronous generator, comprising:

[0007] A frequency coordination control method for a three-machine virtual synchronous generator includes:

[0008] Control data is obtained from a three-machine virtual synchronous generator island system;

[0009] The deviation between the virtual synchronous generator and the average angular velocity is calculated based on the actual angular velocity of each virtual synchronous generator. The virtual dynamic mutual damping torque compensation is generated in real time through the virtual dynamic mutual damping algorithm, and the frequency deviation of each virtual synchronous generator is calculated at the same time.

[0010] The rotor motion equation of the virtual synchronous generator is compensated by virtual dynamic mutual damping torque compensation.

[0011] The compensated virtual synchronous generator rotor motion equation is used as the prediction model, and a multi-objective cost function is constructed with the goal of minimizing the frequency deviation and the synchronous multi-machine frequency.

[0012] Solve for the optimal active reference power of each virtual synchronous generator;

[0013] The optimal active power reference is input into the rotor motion equations of each virtual synchronous generator to achieve frequency closed-loop control.

[0014] Preferably, the control data includes the actual frequency, rated frequency, moment of inertia, damping coefficient, active reference power, and load power of the virtual synchronous generator.

[0015] Preferably, the actual frequency of the virtual synchronous generator is obtained through the following methods:

[0016] The frequency is collected in real time through the frequency detection module at the output of the rotor motion equation of the virtual synchronous generator.

[0017] Preferably, the active power reference of the virtual synchronous generator is obtained through the following methods:

[0018] Active power data is collected in real time through the active power detection module at the output end of the virtual synchronous generator active power frequency loop.

[0019] Preferably, the process of generating the virtual dynamic mutual damping torque compensation includes:

[0020] Based on the deviation between the actual angular velocity calculation and the average angular velocity value of each virtual synchronous generator, the virtual mutual damping factor is used as a weighting coefficient to generate the virtual dynamic mutual damping torque compensation.

[0021] Preferably, the process of building the prediction model includes:

[0022] Based on the modified rotor motion equation of the virtual synchronous generator, a discretized prediction model is established. Based on the current frequency data, historical frequency data and virtual dynamic mutual damping torque compensation, the frequency sequence of each virtual synchronous generator in the next few sampling periods is predicted.

[0023] A nonlinear amplification operator is introduced into the prediction model to avoid under-optimization and over-adjustment in the simulation prediction.

[0024] Calculate the integral compensation term for each virtual synchronous generator. When the frequency deviation is less than or equal to the frequency deviation threshold, the integral compensation term is cleared to zero. When the frequency deviation is greater than the frequency deviation threshold, the integral compensation term accumulates the deviation portion exceeding the frequency deviation threshold.

[0025] Preferably, the multi-objective cost function introduces frequency deviation penalty weight, power adjustment penalty weight, multi-machine frequency synchronization penalty weight, and multi-machine frequency synchronization deviation threshold to balance accurate frequency convergence, smooth power adjustment, and multi-machine synchronization.

[0026] Preferably, the process of solving for the optimal active reference power includes:

[0027] Under constraints, the optimal active reference power that minimizes the multi-objective cost function is obtained through rolling optimization, and the active reference power input of each virtual synchronous generator is updated in real time.

[0028] Preferably, the frequency closed-loop control includes a dynamic adjustment strategy to adapt to sudden load changes, wherein:

[0029] When a sudden load change is detected, the virtual mutual damping factor is temporarily increased, and the weights of the multi-objective cost function are adjusted. The value of the frequency deviation penalty weight is increased to accelerate the frequency convergence speed. After the frequency stabilizes, the initial parameters are restored.

[0030] In addition, the present invention also provides a frequency coordination control system for a three-machine virtual synchronous generator, including a three-machine virtual synchronous generator unit, a filter circuit, a load unit, a frequency detection module, a virtual dynamic mutual damping control module, and a model prediction optimization control module;

[0031] Three-machine virtual synchronous generator unit: By simulating the inertia and damping characteristics of a synchronous generator, it realizes active power output and frequency regulation;

[0032] Frequency detection module: Real-time acquisition of the actual frequency of each virtual synchronous generator to ensure data real-time performance and synchronization;

[0033] Virtual dynamic mutual damping control module: It suppresses frequency fluctuations between multiple generators and blocks the spread of deviations through an active compensation mechanism. It receives frequency data from each virtual synchronous generator in real time, calculates the frequency deviation between multiple generators, generates virtual dynamic mutual damping torque compensation, and suppresses frequency fluctuations and deviation spread.

[0034] Model Predictive Optimization Control Module: Using the motion equation of the virtual synchronous generator rotor after virtual dynamic damping compensation as the prediction model, a multi-objective cost function is constructed, and the optimal active power is solved through rolling optimization to achieve precise frequency convergence;

[0035] Load unit: includes fixed load and sudden change load, used to simulate load change conditions in actual operation and to test the disturbance rejection capability of the control strategy.

[0036] The present invention provides a frequency coordination control method for a three-machine virtual synchronous generator. By using virtual dynamic mutual damping to couple the frequency deviation of multiple machines in real time, it effectively suppresses transient fluctuations and the spread of frequency deviations among multiple machines, thereby improving the system's anti-disturbance capability. By constructing a multi-objective cost function through MPC, it optimizes the frequency deviation that exceeds the reasonable range, enabling the frequency to converge accurately to the reasonable range. The two control strategies work together to solve the defects of traditional multi-machine VSG control, such as frequency offset and large transient fluctuations, and to make up for the lack of synchronization of multiple machines under load fluctuations. It optimizes the power distribution and frequency coordination among the three VSGs, significantly improving the system's operational stability, synchronization, and economy. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A flowchart of a frequency coordination control method for a three-machine virtual synchronous generator provided in an embodiment of the present invention;

[0039] Figure 2 This is a waveform diagram of the frequency response before optimization under the load change condition in an embodiment of the present invention;

[0040] Figure 3 This is a waveform diagram of the optimized frequency response under sudden load change conditions in an embodiment of the present invention. Detailed Implementation

[0041] The core of this invention is to provide a frequency coordination control method for a three-machine virtual synchronous generator (VSG) of permanent magnet synchronous motors. In the prior art, sudden load changes in traditional distributed generation systems often cause power frequency oscillations, and in some cases, one VSG may bear most of the load, which can easily damage the system's power electronic equipment and ultimately lead to system instability and safety hazards.

[0042] The method of this invention is based on a three-machine VSG frequency coordination control strategy using virtual dynamic mutual damping and MPC. It achieves multi-machine frequency deviation coupling compensation through virtual dynamic mutual damping, and combines the rolling optimization characteristics of MPC to dynamically coordinate the active power reference of the three-machine VSG. This not only achieves accurate convergence of system frequency, but also suppresses transient fluctuations and multi-machine frequency deviation, and improves the adaptability of the three-machine VSG islanded system to sudden load changes.

[0043] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1:

[0045] Please refer to Figure 1 , Figure 1 This is a flowchart of a three-machine virtual synchronous generator frequency coordination control method provided in an embodiment of the present invention.

[0046] See Figure 1 In this embodiment of the invention, a frequency coordination control method for a three-machine virtual synchronous generator includes:

[0047] S1: Obtain control data from the three-machine virtual synchronous generator island system.

[0048] In this embodiment, the control data includes the actual frequency of the virtual synchronous generator. f i ( i =1,2,3), rated frequency f n (50Hz), moment of inertia J i Damping coefficient D i Active reference power P refi Load power P load wait.

[0049] Preferably, the actual frequency of the virtual synchronous generator f i The methods of obtaining it include:

[0050] The frequency is collected in real time through the frequency detection module at the output of the rotor motion equation of the virtual synchronous generator.

[0051] Preferably, the active reference power of the virtual synchronous generatorP refi The methods of obtaining it include:

[0052] The active power detection module at the output of the virtual synchronous generator's active power frequency loop collects data in real time, ensuring the real-time and synchronous nature of the data and providing accurate status feedback for multi-machine collaborative control.

[0053] S2: Calculate the deviation between the virtual synchronous generator and the average angular velocity based on the actual angular velocity of each virtual synchronous generator, and generate the virtual dynamic mutual damping torque compensation amount in real time through the virtual dynamic mutual damping algorithm. T Hi Simultaneously, the frequency deviation of each virtual synchronous generator is calculated.

[0054] In this embodiment, the process of generating the virtual dynamic mutual damping torque compensation includes:

[0055] To suppress the spread of frequency deviation among multiple generators and improve synchronization, a virtual mutual damping factor is used based on the deviation between the actual angular velocity calculation and the average angular velocity value of each virtual synchronous generator. H mi The virtual dynamic mutual damping torque compensation amount is generated as a weighting coefficient, and the calculation expression is as follows:

[0056] ;

[0057] in, T Hi This is the virtual dynamic mutual damping torque compensation amount. H mi This is a virtual mutual damping factor. ω i For each VSG, the actual angular velocity. N This represents the number of VSGs connected in parallel.

[0058] It should be noted that the greater the frequency deviation of a VSG from other units, the greater its dynamic damping compensation, thereby quickly suppressing the spread of frequency deviation.

[0059] S3: The virtual synchronous generator rotor motion equation is compensated by the virtual dynamic mutual damping torque compensation amount. The expression of the corrected virtual synchronous generator rotor motion equation is as follows:

[0060] ;

[0061] in, P ni The rated power of each VSG, P ei For the electromagnetic power of each VSG, ω n The rated angular velocity of the VSG, Ji Let the moment of inertia of each VSG be denoted as . D i Here are the damping coefficients of each VSG. ω i Here are the angular velocities of each VSG.

[0062] S4: Using the compensated virtual synchronous generator rotor motion equation as the prediction model, a multi-objective cost function is constructed with the goal of minimizing the frequency deviation and the synchronous multi-machine frequency.

[0063] In this embodiment, the process of constructing the prediction model includes:

[0064] Based on the modified rotor motion equations of the virtual synchronous generator, a discretized prediction model is established to predict the time domain. N p =8, control time domain N c =2, based on the frequency data of the current and three historical sampling periods and the dynamic damping compensation, predict the future. N p Frequency sequence of each VSG within each sampling period f predi (k) (k=1,2,..., N p This ensures that the prediction model accurately reflects the dynamic characteristics of the system.

[0065] The first-order discretization method is as follows: for the differential terms in the continuous domain, a first-order forward difference approximation is used:

[0066] ;

[0067] in, ω i (k)=2πfi(k) , fi(k) For the first i Taiwan VSG in k The actual frequency at any given moment; ω i (k+ 1 ) For the first k+ Predicted angular velocity at time 1; T s Sampling time.

[0068] Substituting the first-order forward difference formula into the modified rotor motion equation, the discretized prediction model is derived:

[0069] ;

[0070] Furthermore, based on current frequency data, historical frequency data, and virtual dynamic mutual damping torque compensation, the frequency sequence of each virtual synchronous generator is predicted over several future sampling periods. In this embodiment, by... ω i =2πf i Convert angular velocity prediction into frequency prediction sequence f predi (k) The expression is as follows:

[0071] ;

[0072] To avoid under-optimization and over-tuning in MPC, a nonlinear amplification operator is introduced into the prediction model. E(k) The calculation expression is as follows:

[0073] ;

[0074] in, K 1 represents the high-frequency amplification gain. K 2 represents linear gain. It is a frequency deviation sequence.

[0075] It should be noted that the method in this embodiment uses a nonlinear amplification operator. When the frequency deviation of the VSG exceeds 0.2 Hz, the frequency deviation is amplified due to the presence of the operator. This ensures that while accelerating the frequency convergence speed, the difference between the steady-state frequency and the rated frequency is also reduced, avoiding potential optimization deficiencies in MPC control. When the frequency deviation of the VSG is less than 0.2 Hz, a smaller operator value is used to maintain the synchronization and convergence stability of the three machine frequencies. This also ensures that MPC control does not overshoot due to excessive optimization.

[0076] Calculate the integral compensation term for each virtual synchronous generator. When frequency deviation |Δf i | Less than or equal to the frequency deviation threshold f tol When the frequency deviation is zero, the integral compensation term is cleared; |Δf i | Greater than the frequency deviation threshold f tol When the integral compensation term accumulates the deviation exceeding the frequency deviation threshold, the calculation expression for the integral compensation term is as follows:

[0077] ;

[0078] in, signAs a sign function, it ensures that integral compensation is only performed on frequency deviations that exceed a reasonable range.

[0079] Furthermore, the multi-objective cost function in this embodiment introduces frequency deviation penalty weights, power adjustment penalty weights, multi-machine frequency synchronization penalty weights, and multi-machine frequency synchronization deviation thresholds to balance accurate frequency convergence, smooth power adjustment, and multi-machine synchronization. The expression of the multi-objective cost function is as follows:

[0080] ;

[0081] in, H i Represents the multi-objective cost function. Q Weights for frequency deviation penalties; R The power adjustment amount is used as the penalty weight; S Penalty weights for multi-machine frequency synchronization; Δf sync This is the threshold for multi-machine frequency synchronization deviation. f predi (k) For each VSG frequency sequence, P refopti The optimal active power reference sequence for each VSG ( k =1~ N p ; j =1,2,3 and j ≠i).

[0082] S5: Solve for the optimal active reference power of each virtual synchronous generator. P refopti .

[0083] In this embodiment, the process of solving for the optimal active reference power includes:

[0084] Under constraints P refmin ≤P refopti ≤P refmax The optimal active reference power that minimizes the cost function Hi is then obtained through rolling optimization. P refopti It also updates the active power reference input of each VSG in real time to achieve closed-loop frequency control.

[0085] S6: Input the optimal active reference power into the rotor motion equation of each virtual synchronous generator to achieve frequency closed-loop control.

[0086] In this embodiment, the frequency closed-loop control includes a dynamic adjustment strategy to adapt to sudden load changes, wherein:

[0087] When a sudden load change is detected ( |P load (t)-P load (t-1)|>ΔP th , ΔP th To set a load mutation threshold, temporarily increase the virtual mutual damping factor, and simultaneously adjust the weights of the multi-objective cost function, increasing the frequency deviation penalty weight. Q The value of is adjusted to accelerate frequency convergence, and the initial parameters are restored after the frequency stabilizes.

[0088] In the frequency coordination control method for a three-machine virtual synchronous generator proposed in this embodiment, the virtual dynamic mutual damping algorithm dynamically adjusts the damping coefficient by coupling the frequency deviations of multiple machines in real time, thereby suppressing transient fluctuations and deviation propagation; the MPC algorithm, through rolling optimization, ensures that the frequency converges precisely to a reasonable range while maintaining smooth power adjustment. The coordinated operation of these two algorithms achieves multi-objective optimization of the frequency control of the three-machine VSG system.

[0089] Optimize the system frequency response waveform under sudden load changes, such as Figure 2 As shown, the system's steady-state frequency is too high (50.3Hz), and the transient fluctuations are large during load changes (fluctuation amplitude is approximately 0.07Hz), with only moderate frequency synchronization among the three machines; the optimized system frequency response waveform is shown below. Figure 3 As shown, the steady-state frequency converged to 50.12Hz, and the transient fluctuation amplitude during load changes decreased to below 0.025Hz. The frequency curves of the three machines showed almost the same trend, and the synchronization was significantly improved, verifying the effectiveness of the method in this embodiment.

[0090] Example 2:

[0091] This embodiment provides a frequency coordination control system for a three-machine virtual synchronous generator, comprising the following components: a three-machine virtual synchronous generator unit, a filter circuit, a load unit, a frequency detection module, a virtual dynamic mutual damping control module, and a model prediction optimization control module.

[0092] The three-machine virtual synchronous generator unit is the core execution unit. It simulates the inertia and damping characteristics of a synchronous generator to achieve active power output and frequency regulation. In this embodiment, the three-machine virtual synchronous generator unit specifically includes key components such as an active power frequency loop, a rotor motion equation, and a reactive power voltage loop.

[0093] Frequency detection module: Collects key information such as the actual frequency of each VSG in real time to ensure data real-time performance and synchronization.

[0094] Virtual Dynamic Mutual Damping Control Module: The core regulating unit for achieving frequency stability control of a multi-generator parallel VSG system. Its main function is to suppress frequency fluctuations between generators and block the propagation of deviations through an active compensation mechanism, thereby improving the transient stability of the entire parallel system. This module receives frequency data from each virtual synchronous generator in real time, calculates the frequency deviation between generators, generates virtual dynamic mutual damping torque compensation, and suppresses frequency fluctuations and deviation propagation.

[0095] Model Predictive Optimization Control Module: As the core optimization unit for the frequency closed-loop control of the virtual synchronous generator multi-machine parallel system, it receives the adjustment results from the virtual dynamic mutual damping control module. Through model prediction and rolling optimization mechanisms, it achieves precise frequency convergence and a comprehensive improvement in system performance. This module uses the virtual synchronous generator rotor motion equation after virtual dynamic damping compensation as the core prediction model, constructs a multi-objective cost function, and solves for the optimal active power reference through rolling optimization to achieve precise frequency convergence.

[0096] Load unit: includes fixed load and sudden load, simulates load change conditions in actual operation, and tests the disturbance rejection capability of the control strategy.

[0097] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0098] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A frequency coordination control method for a three-machine virtual synchronous generator, characterized in that, include: Control data is obtained from a three-machine virtual synchronous generator island system; The deviation between the virtual synchronous generator and the average angular velocity is calculated based on the actual angular velocity of each virtual synchronous generator. The virtual dynamic mutual damping torque compensation is generated in real time through the virtual dynamic mutual damping algorithm. At the same time, the frequency deviation of each virtual synchronous generator is calculated. The rotor motion equation of the virtual synchronous generator is compensated by virtual dynamic mutual damping torque compensation. The compensated virtual synchronous generator rotor motion equation is used as the prediction model, and a multi-objective cost function is constructed with the goal of minimizing the frequency deviation and the synchronous multi-machine frequency. Solve for the optimal active reference power of each virtual synchronous generator; The optimal active power reference is input into the rotor motion equations of each virtual synchronous generator to achieve frequency closed-loop control.

2. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 1, characterized in that, The control data includes the actual frequency, rated frequency, moment of inertia, damping coefficient, active reference power, and load power of the virtual synchronous generator.

3. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 2, characterized in that, The methods for obtaining the actual frequency of a virtual synchronous generator include: The frequency is collected in real time through the frequency detection module at the output of the rotor motion equation of the virtual synchronous generator.

4. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 2, characterized in that, The methods for obtaining the active power reference of a virtual synchronous generator include: Active power data is collected in real time through the active power detection module at the output end of the virtual synchronous generator active power frequency loop.

5. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 1, characterized in that, The process of generating virtual dynamic mutual damping torque compensation includes: Based on the deviation between the actual angular velocity calculation and the average angular velocity value of each virtual synchronous generator, the virtual mutual damping factor is used as a weighting coefficient to generate the virtual dynamic mutual damping torque compensation.

6. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 1, characterized in that, The process of building a predictive model includes: Based on the modified rotor motion equation of the virtual synchronous generator, a discretized prediction model is established. Based on the current frequency data, historical frequency data and virtual dynamic mutual damping torque compensation, the frequency sequence of each virtual synchronous generator in the next few sampling periods is predicted. A nonlinear amplification operator is introduced into the prediction model to avoid under-optimization and over-adjustment in the simulation prediction. Calculate the integral compensation term for each virtual synchronous generator. When the frequency deviation is less than or equal to the frequency deviation threshold, the integral compensation term is cleared to zero. When the frequency deviation is greater than the frequency deviation threshold, the integral compensation term accumulates the deviation portion exceeding the frequency deviation threshold.

7. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 6, characterized in that, The multi-objective cost function introduces frequency deviation penalty weight, power adjustment penalty weight, multi-machine frequency synchronization penalty weight, and multi-machine frequency synchronization deviation threshold to balance accurate frequency convergence, smooth power adjustment, and multi-machine synchronization.

8. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 7, characterized in that, The process of finding the optimal active reference power includes: Under constraints, the optimal active reference power that minimizes the multi-objective cost function is solved through rolling optimization, and the active reference power input of each virtual synchronous generator is updated in real time.

9. The frequency coordination control method for a three-machine virtual synchronous generator according to claim 8, characterized in that, Frequency closed-loop control includes a dynamic adjustment strategy to adapt to sudden load changes, wherein: When a sudden load change is detected, the virtual mutual damping factor is temporarily increased, and the weights of the multi-objective cost function are adjusted. The value of the frequency deviation penalty weight is increased to accelerate the frequency convergence speed. After the frequency stabilizes, the initial parameters are restored.

10. A frequency coordination control system for a three-machine virtual synchronous generator, characterized in that, It includes a three-machine virtual synchronous generator unit, a filter circuit, a load unit, a frequency detection module, a virtual dynamic mutual damping control module, and a model prediction optimization control module; Three-machine virtual synchronous generator unit: By simulating the inertia and damping characteristics of a synchronous generator, it realizes active power output and frequency regulation; Frequency detection module: Real-time acquisition of the actual frequency of each virtual synchronous generator to ensure data real-time performance and synchronization; Virtual dynamic mutual damping control module: It suppresses frequency fluctuations between multiple generators and blocks the spread of deviations through an active compensation mechanism. It receives frequency data from each virtual synchronous generator in real time, calculates the frequency deviation between multiple generators, generates virtual dynamic mutual damping torque compensation, and suppresses frequency fluctuations and deviation spread. Model Predictive Optimization Control Module: Using the motion equation of the virtual synchronous generator rotor after virtual dynamic damping compensation as the prediction model, a multi-objective cost function is constructed, and the optimal active power is solved through rolling optimization to achieve precise frequency convergence; Load unit: includes fixed load and sudden change load, used to simulate load change conditions in actual operation and to test the disturbance rejection capability of the control strategy.

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