Abstract:
As the penetration rate of new energy wind power increases,the equivalent inertia of the new energy power system gradually decreases,which leads to the deterioration of frequency response.The use of wind turbine rotor kinetic energy for auxiliary frequency regulation has become the current mainstream.The problem of secondary frequency drop is caused,which brings new challenges to the control strategy and exit strategy of the wind turbine converter.To this end,the classical response model of the system and the internal delay process of traditional thermal power units are firstly analyzed,and a primary frequency regulation strategy considering the coordination of thermal power units is proposed to improve the primary frequency regulation effect of the system,in which wind turbine is coupled with inertia delay process of synchronous generator set.In order to effectively use the available rotor kinetic energy reserve to find the optimal frequency regulation coefficient,particle swarm optimization(PSO)is used to optimize the output of the wind turbine under the condition of stable wind speed,and the frequency regulation K
cvalue size and specific exit time is determined by satisfying the system conditions such as the frequency minimum point,ROCOF,etc.And use the segmented energy drop signal to act on the converter control to improve the rotor speed recovery,thereby reducing the frequency secondary drop depth.Finally,the proposed scheme is verified in the 4-machine 2-zone power grid model established by Matlab/Simulink simulation software,which provides a basis for new energy to participate in the frequency regulation of the system.