Active Frequency Support Control Strategy Of Microgrid Based On Wind Power Prediction

In recent years,renewable energy sources such as wind power have developed rapidly,and the utilization of large-scale wind power has shown obvious social and environmental benefits.However,the active output of wind turbines has the characteristics of strong randomness,fluctuation and intermittence.The integration of wind power will bring great challenges to frequency control of micro-grid system.Among them,the system frequency based on active power balance is most significantly affected by the uncertainty of active power output of wind turbines.In order to improve the frequency stability of the system when wind power is connected,it is of great significance to study and improve the frequency control method of the microgrid.In this paper,the active control strategy of frequency is studied around the microgrid system with wind turbines.The paper mainly includes the following contents:1)Take the microgrid system with wind turbines as the research object.In order to reduce the adverse effect of wind power fluctuation on the system frequency,a microgrid frequency control strategy based on wind power prediction is proposed.The Kalman filter algorithm is used to predict the wind power,and then the predicted wind power is used to design the frequency controller.The phase compensation is introduced in the designed frequency controller based on the established microgrid frequency control model to improve the dynamic response of the frequency.Taking the four-area interconnected microgrid as an example,the simulation analysis is carried out.The results show that the proposed frequency control strategy considering wind power prediction can effectively reduce the frequency fluctuation of the microgrid system,and its control effect is obviously better than the conventional PID frequency control.2)For wind turbines operating in maximum power tracking mode,a frequency control strategy for microgrid with wind turbines based on model predictive control is proposed.The strategy considers the dynamic characteristics of the wind turbine and predicts the output power of the wind turbine,so it improves the frequency response of the system.First,the frequency response model of the whole system including the frequency control of microgrid and the wind turbine model is established.The system's prediction model is obtained by discretizing the frequency response model.The prediction model is used to predict the system state and response of the next predicted time domain.Using this prediction information,the control signals of the system are optimized to improve the frequency response of the system.On this basis,a model prediction frequency strategy based on prediction model and the optimization of control sequence is proposed.Using wind speed information,the control strategy predicts the state and response of the system and adjusts the control signal based on wind power fluctuations.Finally,the effectiveness and feasibility of the proposed strategy are verified by simulation.3)A frequency control strategy based on model prediction control of wind turbines participation is proposed for wind turbines with frequency modulation capacity under load shedding mode.Firstly,the frequency response model of microgrid frequency control with load shedding wind turbines is established.Based on this model,the system prediction model is derived.Then,the prediction model is used to predict the state and response of the system,and according to the prediction information of the system,the rolling optimization of the control signal is performed to enable the wind turbine output the fixed wind power to suppress of the system frequency fluctuation.Finally,the strategy is verified in a single-area and fourarea microgrid system.The results show that the strategy makes full use of the frequency modulation capability of wind turbines and reduces the frequency fluctuation of the system.