Research On Frequency Regulation Control Strategy For Wind Farm Considering Wind Turbine Load

As a clean and reliable renewable energy,wind energy has been rapidly developed and utilized,and has become a very important energy resource.However,due to the uncertainty and instability of wind energy,it is more difficult to use wind energy.The higher the proportion of wind power integration,the greater the impact on the safe and stable operation of power grid.Wind farms participating in grid frequency regulation can stabilize the grid frequency.However,in the process of frequency regulation,the wind turbine needs to continuously pitch and change speed,which increases the load of the unit and reduces its operating life.Therefore,it is very meaningful to study the frequency modulation control strategy of wind farm considering the unit load.In order to realize frequency regulation and load shedding of wind farm,the operation characteristics of wind turbine under different conditions and the causes of load generation are analyzed.On this basis,the calculation method of the fatigue load of the wind turbine is studied,and the coupling relationship between the electromechanical variables of the wind turbine is considered.The control model of the wind turbine is built,which lays the foundation for the study of the frequency modulation and load shedding control strategy of the wind farm.Aiming at the problem of long time for wind farms to participate in power grid frequency regulation based on traditional PI control strategy,a wind farm active power control method combining model predictive control and unit state classification is studied.Firstly,the principle of frequency modulation control of wind farm is analyzed in detail,and the equivalent model of wind farm is established based on the unit state classification considering the difference of unit operation.Then,a three-layer control structure is studied.The three-layer control structure is composed of power distribution module based on wind turbine state classification,MPC control module of all kinds of units and distribution module of the same level units.Finally,by comparing the simulation results of MPC control strategy and traditional PI control strategy,the effectiveness and superiority of MPC control strategy are verified.In order to reduce the fatigue load of wind turbines under frequency regulation,an active power control method supporting wind farms to participate in grid frequency regulation is studied.Firstly,the fuzzy PID control method is used to adjust the grid frequency to maintain the balance between power generation and grid load,so as to achieve fast power response and reduce frequency deviation.Secondly,the explicit analysis equation of fatigue load sensitivity is derived,which is used to calculate the relationship between the spindle torque and tower bending moment and the power reference value.Then,the reference power of wind turbine is optimized by establishing the objective function.The fatigue load is reduced by power distribution,and the objective function is optimized by using the accelerated particle swarm optimization algorithm to minimize the fatigue load.Finally,the effectiveness of the proposed method is verified by comparing the frequency response of wind farm and the equivalent damage load of wind turbine.