Frequency Security-Constrained Coordinated Optimal Configuration of Multi-Type Flexible Resources

Abstract

With the large-scale integration of converter-based renewable energy sources replacing conventional units, the risks of power system supply–demand imbalance and post-contingency frequency instability have increased dramatically. Expanding the flexible resource portfolio and achieving coordinated optimization of operation and frequency response between newly installed flexible resources and existing resources has thus become a critical issue. This paper proposes a coordinated optimal configuration method for multi-type flexible resources considering frequency security. The operational model for candidate flexible resources, including gas-fired units, electrochemical energy storage, and pumped storage, is established, and their frequency regulation control strategies are embedded into the frequency dynamics of existing resources. Consequently, the system frequency security constraints and analytical models of unit-level nonlinear limiters are derived for optimal planning scenarios, ensuring that the frequency regulation reserve capacity of resources matches the power margin required for transient response. Building upon the above models, a coordinated optimal configuration model is developed that integrates investment decisions of candidate flexible resources, system operation, and frequency security. To address the challenge of embedding the highly nonlinear frequency security constraints directly into the optimization framework, a piecewise linearization reformulation technique is employed to convert them into linear constraints. The numerical simulation verifies the effectiveness of the proposed method.