Energy-Based Maximum Power Point Tracking and Stability Assessment of a 15 MW Offshore Wind Turbine Equipped with a Permanent Magnet Synchronous Generator

This paper investigates maximum power point operation in a large-scale offshore wind energy conversion system equipped with a permanent magnet synchronous generator (PMSG). The study focuses on a 15 MW reference offshore wind turbine and aims to determine the operating conditions required for maximum energy extraction under variable wind speeds. Mathematical models of the wind turbine and the generator are developed using selected parameters derived from the International Energy Agency (IEA) 15 MW Reference Wind Turbine, while the operating characteristics are represented by a simplified analytical model. Based on these models, the turbine and generator power characteristics are derived and the equivalent generator load resistance values corresponding to maximum power point operation are determined. Dynamic simulations are performed for several wind speed profiles to evaluate the evolution of the operating point and the associated stability properties. The analysis reveal two equivalent resistance solutions, with the higher value providing stable operation under wind-speed variations and the lower value defining a potentially unstable operating branch. Furthermore, an energy-based control strategy is proposed to compensate for the influence of the large mechanical inertia and to improve maximum power point tracking performance. The proposed model represents a generic 15 MW offshore wind energy conversion system and focuses on the variable-speed operating region and its associated energetic dynamics. The proposed methodology provides a practical framework for energy-based control and stability assessment of next-generation offshore wind turbines rated above 15 MW.