Frequency Support Capability Evaluation of Wind Turbine Generators Considering Captured Wind Energy Loss

With the large-scale integration of wind power into the power grid, it is essential for wind turbine generators (WTGs) to possess the capability to participate in primary frequency control (PFC). One widely applied approach to achieve frequency control is to utilize the rotor kinetic energy of WTGs. In this paper, a mathematical model of WTG's rotor motion during PFC with stepwise inertial control is derived. The model considers the loss of captured wind power during PFC and derives its mathematical expression. Furthermore, the effects of PFC power increment, PFC duration, and initial operating point on the loss of captured wind energy were analyzed. The capability of WTGs to participate in PFC under stepwise inertial control with only rotor kinetic energy is quantitatively determined accordingly. Finally, the accuracy of the evaluation is verified by performing simulations using DIgSILENT/ PowerFactory software.