Voltage and Frequency Stability Constrained Unit Commitment for Power Systems With Heterogeneous Regulation Resources

The growing integration of converter-based renewable energy sources (RESs) and the retirement of conventional units are pushing modern power systems closer to their stability limits. Imposing stability constraints in scheduling models is crucial to maintaining secure operations. This paper develops a novel voltage and frequency stability constrained unit commitment (UC) model for power systems with heterogeneous regulation resources, including synchronous generators (SGs), synchronous condensers, condenser retrofitted SGs, and wind power generators with grid-following or grid-forming converters. The frequency stability constraints encompass critical metrics across the entire frequency response process, effectively capturing the unique dynamics of diverse resources. The voltage stability constraints prioritize the long-term stability of buses with low stability margins, particularly those heavily penetrated by RESs. Furthermore, the proposed model captures the inherent coupling between frequency and voltage stability, offering extensibility for broader applications. To ensure computational efficiency, nonlinear terms in the constraints are linearized using a piecewise linearization algorithm. The proposed two-stage UC model optimizes operational costs while maintaining system stability. Case studies on the modified IEEE 9-bus system and the IEEE RTS-79 system validate the effectiveness of the proposed method.