This work analyzes high-power wind turbines (WTs) from the Oravita region, Romania. These WTs are based on slip ring induction generator with wound rotor and we propose a modified architecture with two power converters on both the stator and on the rotor, functioning at variable wind speeds spanning a large interval. Investigations developed around a realistic WT model with doubly fed induction generator show how WT control enables variable wind speed operations at optimal mechanical angular speed (MAS), guaranteeing maximal power point (MPP), but only up to a critical wind speed value, after which the electrical power must saturate for reliable operation. In this reliable operating region, blade pitch angle control must be enforced. Variable wind speed acts as a time-varying parameter disturbance but also imposes the MPP operation setpoint in one of the two analyzed regions. To achieve null tracking errors, a double integrator must appear within the MAS controller when the wind speed disturbance is realistically modeled as a ramp-like input; however, inspecting the linearized model reveals several difficulties as described in the paper, together with the proposed solution tradeoff. The study developed around the Fuhrlander-FL-MD-70 1.5[MW] WT model shows that several competitive controllers are designed and tested in the identified operating regions of interest, as they validate the reliable and performant functioning specifications.

This paper examines two contradictory aspects of wind turbine operation: the positive aspect of functioning at the maximum power point (MPP) and the negative aspect of power gaps that occur during significant fluctuations in wind speed. The analysis utilizes experimental data from a 2.5 MW wind turbine operating in the Dobrogea region, focusing on identifying the optimal energy zone. To maintain operation within this optimal zone, a control algorithm based on kinetic energies is developed. The control aims to adjust the load on the electric generator in relation to the wind speed value. The proposed approach ensures operation within the MPP through a control algorithm based on kinetic energies, which adjusts the load on the generator according to the wind speed values.

This study investigates the behavior of large-scale wind turbines operating under high wind speed conditions. A particular emphasis is placed on power output limitations and the dynamic adjustment of rotor blade pitch angles to ensure system stability and prevent structural or operational damage. The novelty of this work lies in integrating real operational data with simplified empirical models, C_P(ω) and P_WT(β, V), to identify an energy-efficient operating zone that minimizes curtailment losses. Using experimental data from a 2.5 MW wind turbine located in the Dobrogea region of Romania, the power curves and mechanical behavior under variable pitch control were analyzed. At a wind speed of 16.5 m/s, the theoretical available power exceeded 12 MW, while the measured output was curtailed to 2.52 MW, corresponding to an ≈80% loss due to pitch regulation. The recalculated power coefficient C_P decreased from ≈0.48 at V = 10 m/s to ≈0.28 at V = 16.5 m/s. Polynomial fitting achieved R² = 0.982 and RMSE = 0.014, ensuring accurate representation of experimental data. Results demonstrate significant losses in extractable wind power when the turbine is operated in a curtailed mode due to pitch regulation. Strategies for maintaining maximum power point (MPP) operation are discussed, along with potential implications of coupling turbines with energy storage systems to reduce curtailment effects. The findings contribute to improved wind turbine control strategies in variable and extreme wind environments. The theoretical models developed in this study were validated using real-world data recorded from a GEWE-B2.5-100 wind turbine located in Dobrogea, Romania.