Transient stability analysis of direct-driven wind turbines based on self-synchronous control
Large-scale integration of wind turbines results in the reduction of frequency modulation capability and weakens the power grid strength.The self-synchronous control adopted by direct-driven wind turbines(WTs)can effectively improve the small disturbance stability of the unit and its ability to support the power grid.However,self-synchronous control also brings complex transient stability issues.The WTs transient models were established respectively aiming at two typical control structures(the power self-synchronous and the DC voltage self-synchronous),and the effects of machine-side dynamics and DC capacitance dynamics on the transient characteristics were revealed.Firstly,the synchronous instability risk of direct-driven wind turbines based on power self-synchronous control under frequency drop was analyzed,and results showed that the stability margin under voltage drop would be reduced by the machine-side dynamics.As for the direct-driven wind turbines based on DC voltage self-synchronous control,the risk of DC voltage collapse instability caused by DC capacitance dynamic under transient was revealed.Then,the transient characteristic differences between converter and WTs were summarized and compared,and the transient control design concepts of WTs were discussed.Finally,the time-domain simulations based on Matlab/Simulink were given to verify the accuracy of the theoretical analysis and the effectiveness of the control.
NETL
NSTL
万方数据
