Pricing Frequency Ancillary Services for Low-Inertia Power Systems under Model Nonconvexity

To enhance the frequency stability in low-inertia power systems, system operators incentivize controllable energy resources to defiver the frequency ancillary service in the wholesale electricity market. In this paper, a pricing scheme for frequency ancillary service is established for low-inertia power systems in the day-ahead electricity market. The distinct response characteristics of thermal generators and wind farms are considered in the modeling of the system frequency response, which then forms frequency security constraints for unit commitment (UC). A convex hull pricing model is proposed to address the research gap related to pricing under the nonconvexity of UC scheduling in the frequency ancillary service market. Numerical results demonstrate the effectiveness of the proposed pricing scheme in incorporating renewable sources and addressing nonconvexity issues.