Enhancing Security and Frequency Control: Integrating Wind Turbine Participation in Power Electronics-Controlled Sustainable Grids Operation

In contemporary power systems, security stands out as a paramount concern. With the implementation of climate change policies, the integration of renewable energy sources (RESs) is on the rise. These RESs are primarily linked to the power grid through power electronic converters (PECs), thereby impacting the stability of the power systems frequency. Consequently, it becomes imperative to enable wind turbines (WTs) to actively participate in the frequency response (FR). This article introduces an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(N-1)$ </tex-math></inline-formula> security-constrained unit commitment (SCUC) model incorporating frequency stability (FS) constraints. The model takes into account the involvement of wind farms (WFs) in FR based on the virtual inertia technique. The electromechanical model of the variable speed wind turbine (VSWT) with a doubly-fed induction generator (DFIG) is employed to determine the participation of WFs in FR. To capture the dynamics of frequency, a time-discretized FR model is utilized considering the rate of change of frequency (RoCoF) constraint, frequency nadir constraint, and quasi-steady-state (QSS) frequency deviation constraint. For a more effective contribution of WFs, a simple optimization model for virtual inertia coefficients (VICs) is presented as a pre-process problem. The proposed model is formulated as a mixed-integer linear programming (MILP) problem. To validate its accuracy, the model is implemented on the IEEE 118-bus test system and solved using CPLEX in the general algebraic modeling system (GAMS). Simulation results demonstrate that the proposed model ensures FS for single-unit outages without operator intervention, achieving a 79% reduction in total security costs compared to traditional frequency constrained UC models. The incorporation of WFs equipped with virtual inertia controllers results in improved FR and increased renewable penetration.