Wind Farm Active Power Control Method In Power System Frequency Regulation

With the maturation of wind power technology and the rapid development of the wind power industry,wind power generation is considered to be the most promising new energy power generation type.In recent years,many countries in the world have vigorously developed wind power generation,and the scale of wind power generation has been increasing year by year.The penetration level of wind power in the power grids of these countries has also increased.The power grid systems also raise higher and higher requirements on the integration of wind farms into the power grid and participation in power grid services,requiring that wind farms can participate in power grid frequency regulation services on the basis of stable output power,just like conventional power plants.How to make full use of wind turbine generating capacity,response characteristics,and operating state information under conditions of random wind speed fluctuations and respond quickly to grid frequency change is a problem that wind farms need to solve in order to participate in grid frequency regulation.In order to solve the above problems,this paper focuses on the research on the method of quickly participating in the primary and secondary frequency regulation control methods of wind farms.The main research contents are as follows:First,the research status of domestic and foreign wind farms participating in power grid frequency regulation is summarized.The problems in existing researches of wind farms participating in grid frequency regulation are analyzed.Combined with the characteristics of different process of power grid frequency regulation,the control objectives and overall scheme of wind farms participating in primary frequency regulation and secondary frequency regulation is proposed.Second,aiming at quick mitigating frequency change problem of wind farms participating in primary frequency regulation,an active power control method to provide spontaneous simulated inertia response with wind turbine deloaded operation is proposed.The deloading curve of the wind turbine operating under low wind speed is designed.The deloaded operating wind turbines are choosing the wind turbines under low wind speed preferentially to avoid the slow response of the wind turbines under high wind speed due to pitch action.A simulation inertia response control method is also designed.The wind turbines use the rotor speed change to release or absorb kinetic energy to provide short-term active support for the grid.Third,in view of the active power tracking problem of wind farms participating in the secondary frequency regulation,a method of active power control for a wind farm based on model predictive control combined with wind turbine state classification is proposed.The contributions of it are as follows,1)A state classification method and equivalent model of each class of wind turbines for wind farm active power control are developed.2)A three level control structure which is composed by a wind turbine state classification based power dispatching module for each class of wind turbines,distributed MPC controllers for each class of wind turbine and distributed power dispatching modules for wind turbines in same class,is proposed.This method can shorten the setting time of wind farm to track power grid scheduling.Based on the above research work,the primary frequency regulation and secondary frequency regulation control methods studied in this paper are applied to the grid frequency regulation simulation experiment of wind farms which are composed of NREL wind turbines.The experimental results show that the wind farm active power control methods proposed in this paper achieve effective auxiliary frequency services during the primary and secondary frequency regulation process.The rapidity of the wind farm participating in grid frequency regulation is better than the corresponding traditional methods.