Design Of ADRC For Load Frequency Control Of Power Systems With Wind Turbines

Nowada ys wind power is the major renewable energy in tackling global energy shortage.With more and more wind turbines participating in power s ystems,the stability and security of electric power s ystems might be reduced due to the wind's randomness,intermittence and seasons which can lead to the frequenc y output of wind power unsmooth.In order to keep the frequency within the permitted range,load frequenc y control(LFC)of power s ystems with wind turbines should be studied and the load frequenc y controller must be designed to damp the frequenc y fluctuation caused b y wind power.Linear active disturbance rejection control(LADRC)is known for its simplicity and its performance in disturbance attenuation.Currently,the most common wa y of tuning LADRC is via the bandwidth idea,but this method might be conservative for complex plants with uncertain disturbance.In this paper,in order to improve the disturbance rejection performance of LADRC,tuning of LADR C with known plant information is investigated and then load frequenc y control schemes to overcome the interference of wind power are also proposed.Scheme one treats the wind power as the stochastic disturbance to the LFC s ystems.To handle the stochastic disturbance,an LQG controller is firstly designed to control the LFC system with wind turbine,then the designed LQG controller is converted to a conventional LADRC without degrading performance in disturbance attenuation,so the LADRC can maintain the same propert y of rejecting stochastic disturbance with the LQG controller.This design method improves the stochastic disturbance rejection performance of LADRC.Scheme two treats the wind power as the uncertain disturbance to the LFC s ystems.To handle the uncertain disturbance,a disturbance observer(DOB)is designed for the LFC s ystem,then the designed system is converted to a two degree-of-freedom control s ystem from which a conventional LADRC can be obtained without degrading performance in disturbance attenuation,so the LADRC also maintains the same propert y of rejecting uncertain disturbance with DOB.This design method improves the performance of LADRC in rejecting wind power disturbance as well.Finall y the models of wind power generation system and LFC system are built up.The proposed LADRC schemes are used.Simulations of two proposed methods show the good control performance,disturbance rejection performance and robustness,which prove the feasibility of LQG-LADRC and DOB-LADRC design methods.