Modeling the Coupling of Rotor Speed, Primary Frequency Reserve and Virtual Inertia of Wind Turbines in Frequency Constrained Look-Ahead Dispatch

With the increasing penetration of wind power, wind turbines (WTs) are required to provide primary frequency reserve (PFR) and virtual inertia support to the grid to ensure frequency security. However, in existing frequency-constrained scheduling research, the coupling of WTs' rotor speed, PFR and virtual inertia has been overlooked. This paper accurately models the PFR capacity and virtual inertia of WTs based on WT's rotor speed control and frequency control. Besides, a frequency-constrained stochastic look-ahead economic dispatch (FCS-LAED) model, which co-optimizes the PFR, virtual inertia and rotor speed of WTs is proposed. In this model, WTs' operation constraints are considered more comprehensively compared with existing research. A combination of convex hull relaxation and McCormick envelope is employed to convexify the proposed FCS-LAED model. To further tighten the relaxation, a modified sequential bound tightening method is proposed. Case studies on the modified IEEE 6-bus system and IEEE 118-bus system verify the effectiveness of the proposed model and methods.