Influence and Countermeasure of Increasing Wind Penetration on Frequency Control

The number of wind turbines connected to electric power grid is steadily increasing, which detrimentally affects the system frequency characteristics, and consequently limits the maximum penetration level of wind generation. Nowadays, contribution of wind generators to frequency control is required by system operators in many countries. In this paper, in order to increase integration proportion of wind generation, inertial response of wind turbines following frequency disturbance is analyzed from three aspects, including the physical structure, the theory of electrical machine and mechanics theory. Also, influence of wind generation on frequency characteristics is proposed. It is found that frequency problem has been the constraint condition of penetration level of wind generation, which gives rise to demand of wind turbines participating frequency control. Furthermore, countermeasure of wind generation participating frequency control is proposed. Under virtual inertia control, the rate of change of frequency(ROCOF) is reduced, and the time of frequency nadir is delayed. By adding droop control, both the frequency nadir and quasi-steady state frequency are lifted. The implementation of virtual inertia control and droop control can increase penetration level of wind generation as well as guarantee power system security.