Research On Primary Frequency Regulation Strategy Of Grid-friendly Wind Farms

With the gradual increase in the proportion of renewable energy,wind power has been widely used as an important renewable energy generation method.However,due to natural factors such as wind speed,the active power output of wind turbines exhibits strong fluctuations and randomness,which can severely impact the stability of the power grid frequency when directly integrated into the grid.Moreover,the large-scale integration of wind power further reduces the inertia of the power system.To alleviate the pressure of wind power integration on the grid and optimize wind power’s active output,this paper starts from the two aspects of wind power’s own power fluctuation and frequency response ability to improve the reliability and anti-interference ability of the power system.The paper’s main research content and innovative points are as follows:(1)An active optimization control strategy of wind farm based on load reduction and smooth synergy is proposed,and a multi-objective function to quantitatively measure the contribution of wind farm to power balance of the power grid is constructed.Firstly,the coordinated control of overspeed and pitch is used to reserve the active standby of wind power,secondly,the lower envelope curve of the offloaded power is solved by cubic spline interpolation to smooth the fluctuation of power,and finally the optimal grid-connected power is solved after optimization.This strategy can not only improve the smoothing effect of wind power but also improve the active standby margin.(2)A fuzzy droop control strategy considering power backup margin is designed to solve the problem of over-response and under-response caused by uneven distribution of active power reserve margin.The fuzzy rule is established by using the characteristic relationship between power margin and frequency deviation and sag coefficient,and the sag coefficient is adjusted adaptively through fuzzy control to ensure that the active standby of the wind farm can be fully utilized.(3)Taking a 50MW wind farm as an example,the effectiveness of the proposed strategy is verified.Firstly,the influence of wind farms on grid frequency when connected to the grid under three different control strategies is compared.Secondly,two load disturbances were added to the simulation experiment to analyze the primary frequency regulation results of the wind farm.Comparing the active margin and active increment of wind farms and the frequency response results under the three control strategies,the simulation results show that under the optimized control strategy in this paper,the wind farm causes the least fluctuation of the power grid frequency,and can provide more active support capacity,which has obvious advantages in primary frequency regulation.