Frequency Security-Constrained Unit Commitment With High Shares of Renewable Energy

With the increasing integration of renewable energy sources, power systems face significant challenges in maintaining frequency stability due to reduced system inertia. To address these challenges, this paper proposes a frequency-constrained unit commitment (UC) model that incorporates virtual inertia (VI) support from distributed energy resources and frequency security constraints. The model employs a piecewise linearization (PWL) method to approximate nonlinear frequency constraints (FC), enabling efficient integration into a mixed-integer linear programming (MILP) framework. The proposed approach is validated on a modified IEEE 30-bus system. Results demonstrate that adding frequency constraints improves system inertia levels, ensures frequency stability during disturbances and mitigates risks of large-scale power outages. While this increases operating costs by 8%, the enhanced reliability and reduced outage risks justify the trade-off.