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Wind energy is one of the most important clean energies and the variable speed constant frequency technology is widely used in wind energy conversion systems. Maximum power point tracking (MPPT) is essential for a variable speed constant frequency wind power generation system. Concerning the current research on the MPPT algorithm, this paper studies the principle, characteristics, and reported improvement strategies of principal algorithms.

Maximum power point tracking (MPPT) is the key to improve the conversion efficiency of wind energy. Concerning the current research on the MPPT control, based on the accurate tracking of rotor speed probability density function (PDF) shape for wind turbines, a novel MPPT algorithm was introduced in detail to improve the power capture and reduce mechanical damage for wind turbines. Considering the influence of wind speed distribution on the wind power generation system performance, this paper expounds a PDF shape control method of a stochastic system based on the Fokker–Planck–Kolmogorov (FPK) equation. Combining the conventional optimal torque (OT) control algorithm with the FPK equation solved by linear least-square (LLS) method, the novel MPPT control law is designed to make the PDF shape of rotor speed track the desired PDF shape as accurately as possible. The simulation verification of the novel MPPT method is carried out in the 1.5 MW wind turbine system. The results reveal that the novel MPPT method can improve the conversion efficiency of wind energy, reduce the frequent fluctuations of system variables, and significantly optimize the performance of wind power generation system.

This article investigates the adaptive event-triggered fuzzy control problem for vehicle suspension systems with nonlinear characteristics and time delay. First, to describe the vehicle suspension system with nonlinear components, a Takagi-Sugeno fuzzy suspension model is established via local linear regression method. Second, considering that the communication bandwidth is limited, an adaptive event-triggered strategy is employed to acquire a higher efficiency in terms of saving the transmission resource. Third, based on a time-delay principle and Lyapunov stability theory, a co-design method is proposed to obtain the event generator and the fuzzy controller simultaneously. The proposed event-triggered fuzzy control method is effective to improve performances of the suspension system and guarantee the limits of suspension travel and tire deflection. Finally, compared with the existing method, the effectiveness of the proposed method is verified by simulation tests with various road disturbances.