Double Level Distribution Strategy Of Wind Farm Considering Dynamic Characteristics Of Active Power Control Of Wind Turbines

With the rapid development of modern wind power technology,the influence of largescale wind power access on the frequency stability of power grid is increasingly prominent.Therefore,it is necessary to involve wind power in the Automatic Generation Control(AGC)of the power grid,so as to alleviate the frequency modulation pressure of the power grid.In this context,wind farms need to rationally distribute power instructions from power grid dispatching center according to wind speed environment and operation state of each unit in the field.In order to improve the power response performance of the wind farm participating in the AGC,the active power control strategy of the wind farm and its dynamic characteristics were deeply considered in the process of designing the active power distribution strategy of the wind farm.Based on this,the double-layer active power distribution strategy of the wind farm based on the wind wheel speed was proposed.The specific work is as follows:In terms of the active power control strategy of the unit,this paper firstly compared the power response performance of Pitch Angle Control(PAC)and Rotor Speed Control(RSC),and found the advantage of RSC method in maintaining constant unit output with variable speed of the rotor.Furthermore,in view of the problem of setting the reference power in the RSC method,the research pointed out the shortage of predicting the active power output capacity of the unit based on the wind speed information,and then analyzed the advantages of using the rotor speed information to substitute the wind speed information to describe the unit output capacity.On this basis,this paper puts forward a new idea of applying the rotor speed to active power distribution of wind farm,and verifies the feasibility of applying the rotor speed through simulation examples.Combined with the advantages of the rotor speed in active power distribution of wind farms,this paper proposes a two-layer distribution strategy for wind farm considering dynamic characteristics of active power control of unit,including the optimal upper layer distribution strategy for long time scale and the real-time correction strategy for lower layer for short time scale.Among them,the upper layer optimal distribution comprehensively examined the constraints of wind power generation error,unit start and stop time and power command amplitude,making the power command distribution result more reasonable.Fuzzy control is introduced for the real-time correction of the lower layer,and the real-time rotor speed change of the unit is taken as the input to determine the correction amount of the power instruction,so as to ensure the stable operation of the unit in the process of responding to the power instruction.Finally,the wind farm simulation model was built by Matlab/Simulink,and the feasibility and superiority of the proposed distribution strategy were verified by comparing the influence of the overall output of the wind farm,unit response performance,unit real-time rotor speed and correction period with the traditional distribution method.