Research On Wind Farm Participating In Secondary Frequency Regulation Control Of Power Grid

In recent years,with the rapid development of the wind power industry,wind power is one of the most promising resources in new energy.In recent years,the scale of wind power has been increasing year by year,and the proportion of wind power in the power grid is increasing.There is an urgent need for wind storage joint farms to participate in power grid frequency regulation services and provide power support to maintain frequency stability of the power grid.Under wind speed fluctuations,how to fully utilize the response characteristics and power support capabilities of wind turbines and energy storage systems based on operational status information,quickly respond to the secondary frequency regulation of the power grid,and track the power command values issued by the higher-level system is an urgent problem that wind farms need to solve for power control.This article establishes a multi-agent and multi-objective optimization strategy based on wind farms and energy storage systems,and studies the control of wind storage joint systems participating in secondary frequency regulation of the power grid.The main research content of this article is as follows:Firstly,the current research status of wind farms and energy storage systems participating in grid frequency regulation at home and abroad was summarized,and the advantages and disadvantages of control strategies and optimization algorithms used in existing research were analyzed.Then,in order to coordinate the power optimization allocation of various wind turbines in the wind farm and meet the power command value issued by the wind farm’s tracking superior system,the load shedding operation of the wind turbines was achieved by reserving the initial pitch angle.By controlling the pitch angle to release and absorb wind energy and provide sufficient power margin for the power grid,a model predictive control method was adopted to establish a prediction model based on the pitch angle of the wind turbine,and a multi-objective wind farm participation in the secondary frequency regulation control strategy of the power grid was developed.Further correction is made to the pitch angle control based on the difference between the active power command value of the superior system and the actual output power of the wind turbine,so that the wind turbine can better track the power command value of the superior system during the secondary frequency regulation period,quickly respond to frequency changes,achieve frequency error free control,and complete the task of secondary frequency regulation.Secondly,a multi-agent and multi-objective secondary frequency regulation control strategy based on model predictive control(MPC)is proposed for wind storage combined electric fields under medium to high wind speeds by analyzing the mechanical characteristics of wind turbines and the operational characteristics of energy storage systems.A predictive model for wind farm pitch angle control and a predictive model for battery energy storage system have been established,and a multi-objective multi-agent optimization strategy has been proposed to optimize the active power output of the wind turbine and energy storage system,reduce changes in wind turbine pitch angle,and reserve reserve capacity for the energy storage system,achieving faster and more accurate power tracking.Thirdly,in response to the issue of wind turbine rotor speed decreasing after participating in frequency regulation during the primary frequency regulation process of wind farms,which may lead to turbine shutdown or secondary frequency drop,a coordinated control strategy for wind storage combined farms participating in the primary and secondary frequency regulation of the power grid was designed.In the primary frequency regulation,a comprehensive inertia control based on model predictive control was adopted,and an appropriate objective function was used,Minimize wind energy loss in wind farms.When the primary frequency regulation is started,the frequency is adjusted through rotor speed control to release the kinetic energy of the fan to release active backup.The rotor speed may experience a drop phenomenon,but after the release of rotor kinetic energy,in order to restore the previous operating state of the rotor,the rotor will absorb active power from the power grid;The secondary frequency regulation adopts pitch angle control,which provides the power value for restoring the rotor speed and restoring the frequency to the rated power value.However,due to the slow adjustment process of pitch angle,a battery energy storage system can also be used to help the wind farm provide power for restoring the rotor speed and quickly restore the rotor speed of the wind turbine.Based on the above research work,the control strategy studied in this paper will be applied to simulation experiments.The simulation results show that the control strategy proposed in this article comprehensively considers the controllable secondary frequency regulation ability of the wind turbine and the fast and accurate tracking characteristics of the battery energy storage system,enabling the wind storage joint farm to actively respond to changes in system frequency,better track the active power command value issued by the superior system,and actively participate in the secondary frequency regulation of the power grid.