Primary Frequency Control Strategy Of Wind Turbine Considering Delaying Support

With the increasing scale of wind power integration,in order to ensure the quality of grid frequency and stability of operation,it is urgent for wind power to participate in primary frequency regulation.At present,primary frequency control strategies based on the kinetic energy release of wind turbine are widely used,which generally have problems of limited available kinetic energy and short active support time.However,most of the existing research require wind turbine to provide active power support immediately when frequency fluctuation occurs.These strategies cause wind turbine to release limited active power prematurely and ignore the coordination between short-term wind turbine output and long-term synchronous generator output at the time level,which may affect the improvement effect of frequency nadir.To solve this problem,by adjusting the starting time of wind turbine providing active support,this paper finds that delaying the time of wind turbine participating in frequency regulation can improve the frequency nadir,and later verifies the generality of this phenomenon under different frequency control strategies and operating conditions through a large number of simulations.Further,by analyzing the output of actuators in the process of frequency regulation,the explanation of mechanism is given how the delay of wind turbine operation leads to the improvement of frequency nadir.By delaying the starting time for wind turbine to participate in frequency regulation,the output of the synchronous generator is increased at the cost of increasing the rate of change of frequency(ROCOF)at the initial stage of frequency response.Meanwhile,more kinetic energy of wind turbine is retained to the later stage of frequency response,so as to avoid the secondary frequency drop caused by its premature release.On this basis,it is speculated and verified that there is an optimal delay time for raising the frequency nadir.And then,the frequency characteristics of power grid under the optimal delay time is analyzed in this paper,according to which an optimal delay time estimation method is proposed.Alteriorly,a primary frequency control strategy of wind turbine considering delaying support is designed.Finally,based on DIg SILENT software and experimental platform for dynamic simulation of power system,the simulation and experiment are completed under different operating conditions.The results show that compared with the control strategy based on immediate support,the strategy of wind turbine considering delaying support proposed in this paper can significantly improve the frequency nadir.