Frequency Modulation Control Of Offshore Wind Power System Based On Intelligent Control

Offshore wind power is a green and renewable energy source,and its proportion in renewable energy has been increasing in recent years.However,with the rapid development of the wind power industry,the loading capacity of offshore wind turbines is increasing,and the demand for frequency control capability of the power grid is also increasing.Therefore,in order to improve the ability of offshore wind turbines to participate in power system frequency regulation after grid connection,this thesis uses doubly fed wind turbines as a carrier to study the control strategies of wind turbines under different frequency conditions.The main work of the thesis is as follows:(1)Taking the Double Fed Induction Generation(DFIG)wind turbine as the research object,establish a mathematical model and study its operating mechanism.Firstly,analyze the operating principle and mathematical model of DFIG,and build a DFIG grid connection simulation model using Matlab/Simulink platform;On this basis,the traditional frequency optimization methods of wind turbines are analyzed through simulation experiments,laying a theoretical foundation for subsequent research on frequency optimization strategies under different frequency conditions.(2)When frequency events occur in the power grid below rated wind speed,this article takes DFIG multiple units as the research object and proposes an Intelligent Bee Colony Auto-Disturbance Inertia Control(ABC-ADRC)virtual inertia control strategy based on the rotor kinetic energy of wind turbines.Firstly,based on the system frequency dynamic response equation,an active disturbance rejection controller(ADRC)is designed according to the nonlinear feedback control law and extended state observer(ESO).Secondly,based on the bee colony algorithm for honey harvesting behavior,the ADRC parameters are iteratively optimized to achieve power sharing and adaptive noise cancellation.Finally,the Matlab/Simulink simulation results show that the proposed ABCADRC can effectively release the rotor kinetic energy and reduce the frequency fluctuation of the wind turbine after grid connection under rated wind speed.(3)When frequency events occur in the power grid above the rated wind speed,this article takes the DFIG blade pitch angle as the research object and proposes a variable pitch control strategy based on Intelligent Particle Swarm Optimization Auto Disturbance Inertia Control(PSO-ADRC)to provide frequency support for the power grid.In this control strategy,an automatic disturbance rejection controller with variable pitch of the wind turbine is first established;Then,genetic algorithm(GA)and particle swarm optimization algorithm(PSO)were used to achieve online tuning of the parameter controller and adaptive output of power.The simulation results show that the proposed control strategy can effectively control the output of active power of the wind turbine and reduce the frequency fluctuation after the wind turbine is connected to the grid above the rated wind speed.(4)In order to further improve the interference capability of offshore wind turbine grid connected systems,a multi-objective frequency regulation strategy based on intelligent model predictive control was studied.The rotor speed,active load shedding,and output power of the wind turbine were taken as the targets for the wind turbine speed recovery interval.A predictive model for model predictive control was established using the frequency model of the wind turbine grid connected system;By constructing an objective function and constraint conditions based on the difference between the real-time speed of the wind turbine and the optimal speed under the MPPT curve,as well as the frequency deviation,the MPC controller solves the control sequence of active power based on the current operating parameters of the wind turbine and the real-time parameters of the power grid frequency,thereby determining the output power of the wind turbine and achieving dynamic stability of the speed recovery process and the power grid frequency.Finally,the multi-objective frequency modulation strategy based on intelligent model predictive control proposed in this thesis was verified through simulation on Matlab/Simulink platform,which not only has good anti-interference performance but also effectively suppresses the secondary drop of power grid frequency.