CN-121840807-B - Frequency coordination control method and system for three-machine virtual synchronous generator

CN121840807BCN 121840807 BCN121840807 BCN 121840807BCN-121840807-B

Abstract

The invention relates to the technical field of new energy, in particular to a frequency coordination control method and a system of a three-machine virtual synchronous generator, wherein the method comprises the steps of obtaining control data of each VSG in a three-machine VSG island system; the method comprises the steps of calculating frequency deviation coupling items among multiple computers in real time, generating virtual dynamic mutual damping torque compensation quantity, constructing a multi-objective cost function by taking a reasonable interval of frequency convergence to the vicinity of a rated value as a target by combining rolling optimization characteristics controlled by MPC, outputting optimized active reference power, and realizing frequency coordination control through the synergistic effect of virtual dynamic mutual damping and MPC. The method solves the problems of serious frequency deviation, excessive transient fluctuation and poor multi-machine synchronism of the three-machine VSG system, enhances the frequency anti-interference capability of the multi-machine system, realizes accurate control of the frequency, and improves the operation stability, synchronism and economy of the three-machine VSG island system.

Inventors

Huo Yiwen
CHEN TAOYI
DING SHUYE
JIANG HAOYAN
DAI LINZHI
ZHANG YIWEN

Assignees

南京师范大学

Dates

Publication Date: 20260512
Application Date: 20260316

Claims (10)

1. The frequency coordination control method of the three-machine virtual synchronous generator is characterized by comprising the following steps of: acquiring control data from a three-machine virtual synchronous generator island system; Calculating the deviation between the virtual synchronous generator and the average angular velocity based on the actual angular velocity of each virtual synchronous generator, generating a virtual dynamic cross damping torque compensation quantity in real time through a virtual dynamic cross damping algorithm, and calculating the frequency deviation of each virtual synchronous generator; Compensating a rotor motion equation of the virtual synchronous generator by using the virtual dynamic mutual damping torque compensation quantity; taking the compensated virtual synchronous generator rotor motion equation as a prediction model, and constructing a multi-objective cost function by taking minimized frequency deviation and synchronous multi-machine frequency as targets; solving the optimal active reference power of each virtual synchronous generator; and inputting the optimal active reference power into a rotor motion equation of each virtual synchronous generator to realize frequency closed-loop control.
2. The method of claim 1, wherein the control data includes an actual frequency, a rated frequency, a moment of inertia, a damping coefficient, an active reference power, and a load power of the virtual synchronous generator.
3. The method for controlling frequency coordination of a three-machine virtual synchronous generator according to claim 2, wherein the method for obtaining the actual frequency of the virtual synchronous generator comprises the following steps: The frequency detection module at the output end of the rotor motion equation of the virtual synchronous generator is used for collecting the signals in real time.
4. The method for controlling frequency coordination of a three-machine virtual synchronous generator according to claim 2, wherein the method for obtaining the active reference power of the virtual synchronous generator comprises the following steps: The real-time collection is performed through an active detection module at the output end of the active frequency loop of the virtual synchronous generator.
5. The method for frequency coordinated control of a three-machine virtual synchronous generator according to claim 1, wherein the process of generating the virtual dynamic cross damping torque compensation amount comprises: And generating a virtual dynamic mutual damping torque compensation quantity by adopting a virtual mutual damping factor as a weight coefficient based on the deviation between the actual angular velocity calculation and the average angular velocity value of each virtual synchronous generator.
6. The method for controlling frequency coordination of a three-machine virtual synchronous generator according to claim 1, wherein the process of constructing the prediction model comprises: Based on the corrected virtual synchronous generator rotor motion equation, a discretized prediction model is established, and based on current frequency data, historical frequency data and virtual dynamic cross damping torque compensation quantity, the frequency sequence of each virtual synchronous generator in a plurality of sampling periods in the future is predicted; introducing a nonlinear amplification operator into the prediction model to avoid insufficient and overshoot of simulation prediction optimization; And calculating integral compensation terms of each virtual synchronous generator, clearing the integral compensation terms when the frequency deviation is smaller than or equal to the frequency deviation threshold value, and accumulating deviation parts exceeding the frequency deviation threshold value when the frequency deviation is larger than the frequency deviation threshold value.
7. The method according to claim 6, wherein the multi-objective cost function introduces a frequency deviation penalty weight, a power adjustment penalty weight, a multi-machine frequency synchronization penalty weight, and a multi-machine frequency synchronization deviation threshold for achieving frequency accurate convergence, power adjustment smoothness, and multi-machine synchronization.
8. The method for frequency coordinated control of a three-machine virtual synchronous generator according to claim 7, wherein solving for the optimal active reference power comprises: under the constraint condition, the optimal active reference power which 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 method of claim 8, wherein the frequency closed loop control comprises dynamically adjusting a strategy to adapt to a load ramp condition, wherein: when the load mutation is detected, the virtual mutual damping factor is temporarily increased, the weight of the multi-objective cost function is adjusted, the value of the frequency deviation punishment weight is increased, the frequency convergence speed is increased, and the initial parameters are recovered after the frequency is stable.
10. The frequency coordination control system of the three-machine virtual synchronous generator is characterized by comprising 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; The three-machine virtual synchronous generator unit realizes active power output and frequency adjustment by simulating inertia and damping characteristics of the synchronous generator; the frequency detection module is used for collecting the actual frequency of each virtual synchronous generator in real time and ensuring the real-time property and synchronism of data; The virtual dynamic mutual damping control module is used for restraining frequency fluctuation among multiple computers through an active compensation mechanism, blocking deviation diffusion, receiving frequency data of each virtual synchronous generator in real time, calculating frequency deviation among the multiple computers, generating virtual dynamic mutual damping torque compensation quantity and restraining frequency fluctuation and deviation diffusion; The model prediction optimization control module takes a virtual synchronous generator rotor motion equation subjected to virtual dynamic damping compensation as a prediction model, constructs a multi-objective cost function, and solves the optimal active reference power through rolling optimization to realize frequency accurate convergence; The load unit comprises a fixed load and a sudden change load and is used for simulating the load change working condition in actual operation and checking the disturbance rejection capability of the control strategy.

Description

Frequency coordination control method and system for three-machine virtual synchronous generator Technical Field The invention relates to the technical field of new energy, in particular to a frequency coordination control method and system for a three-machine virtual synchronous generator. Background Renewable energy sources represented by wind and light are accessed into a power grid in a large scale. The micro-grid as one of the interfaces of distributed power sources (distribute dgeneration, DG) with large grids is a hotspot of research today. When the micro-grid runs off-grid, the voltage, the frequency and the like of the micro-grid are easy to be disturbed and unstable due to lack of necessary inertia. Thus, virtual synchronous generator (virtual synchronous generator, VSG) control with inertial and damping characteristics for distributed power generation systems is distinguished by the introduction of rocking equations in the converters to simulate the transient characteristics of synchronous generators (synchronous generator, SG). The VSG control has the capability of autonomously constructing voltage and actively supporting the power grid, and can remarkably improve the stability of the micro power grid. However, when the converter simulates the SG, the oscillation characteristic of the rotor of the synchronous motor is inevitably introduced, so in a parallel system comprising a plurality of virtual synchronous motors, the power frequency oscillation of the system is often caused when the load suddenly changes, even the situation that one VSG bears most of the load occurs, the power electronic equipment of the system is extremely damaged, the system is finally unstable, and potential safety hazards are caused. In summary, a method and a system for controlling frequency coordination of a three-machine virtual synchronous generator are needed to solve the problem of uneven load of a multi-machine VSG system. Disclosure of Invention The invention aims to provide a frequency coordination control method and system for a three-machine virtual synchronous generator, which are based on a three-machine VSG frequency coordination control strategy of virtual dynamic mutual damping and MPC (model predictive control), realize multi-machine frequency deviation coupling compensation through virtual dynamic mutual damping, dynamically coordinate active reference power of the three-machine VSG by combining rolling optimization characteristics of the MPC, realize accurate convergence of system frequency, inhibit transient fluctuation and multi-machine frequency deviation, and promote adaptability of a three-machine VSG island system to load mutation working conditions. The invention provides a frequency coordination control method and a system for a three-machine virtual synchronous generator, comprising the following steps: A frequency coordination control method of a three-machine virtual synchronous generator comprises the following steps: acquiring control data from a three-machine virtual synchronous generator island system; Calculating the deviation between the virtual synchronous generator and the average angular velocity based on the actual angular velocity of each virtual synchronous generator, generating a virtual dynamic cross damping torque compensation quantity in real time through a virtual dynamic cross damping algorithm, and calculating the frequency deviation of each virtual synchronous generator; Compensating a rotor motion equation of the virtual synchronous generator by using the virtual dynamic mutual damping torque compensation quantity; taking the compensated virtual synchronous generator rotor motion equation as a prediction model, and constructing a multi-objective cost function by taking minimized frequency deviation and synchronous multi-machine frequency as targets; solving the optimal active reference power of each virtual synchronous generator; and inputting the optimal active reference power into a rotor motion equation of each virtual synchronous generator to realize frequency closed-loop control. Preferably, the control data includes an actual frequency, a rated frequency, a moment of inertia, a damping coefficient, an active reference power, and a load power of the virtual synchronous generator. Preferably, the method for obtaining the actual frequency of the virtual synchronous generator includes: The frequency detection module at the output end of the rotor motion equation of the virtual synchronous generator is used for collecting the signals in real time. Preferably, the method for obtaining the active reference power of the virtual synchronous generator comprises the following steps: The real-time collection is performed through an active detection module at the output end of the active frequency loop of the virtual synchronous generator. Preferably, the process of generating the virtual dynamic cross damping torque compensation amount includes: And generating a virtual dynami