ALBERT

Description: This paper studies the fault-tolerant control problem of uncertain doubly-fed wind turbine generation systems with sensor faults. Considering the uncertainty of the system, a fault-tolerant control strategy based on a T-S fuzzy observer is proposed. The fuzzy observer is established based on the T-S fuzzy model of the uncertain nonlinear system. According to the comparison and analysis of residual between the state estimation of the fuzzy observer output and the measured value of the real sensor, a fault detection and isolation (FDI) based on T-S fuzzy observer is designed. Then by using a Parallel Distributed Compensation (PDC) method we design the robust fuzzy controller. Finally, the necessary and sufficient conditions for the stability of the closed-loop system are proved by quoting Lyapunov stability theory. The simulation results verify the effectiveness of the proposed control method.

Description: The problem of robust fault-tolerant control for actuators of nonlinear systems with uncertain parameters is studied in this paper. Takagi–Sugeno (T-S) fuzzy model is used to describe the wind energy conversion system (WECS). Fuzzy dedicated observer (FDO) and fuzzy proportional integral observer (FPIO) are established to reconstruct the system state and actuator fault, respectively. Fuzzy Robust Scheduling Fault-Tolerant Controller (FRSFTC) is designed by parallel distributed compensation (PDC) method, so as to realize the purpose of active fault tolerance for actuator faults and ensure the robust stability of the system. The stability of the closed-loop system is proved by Taylor series, Lyapunov function, and Linear Matrix Inequalities (LMIs). Finally, the simulation results verify that the proposed method is feasible and effective applied to WECS with doubly fed induction generators (DFIG).

Description: Assessment of conservation effectiveness in biodiversity ecological function zones (BEFZs) is important for biodiversity in China. However, a scientific and practical method for effectively comparing biodiversity conservation between different BEFZs is lacking. In this study, a reference condition index that can represent the optimum value of biodiversity in one BEFZ and a conservation effectiveness index that can reflect the effect of conservation measures were developed. Then a method to compare the biodiversity conservation effectiveness between different BEFZs on both temporal and spatial scales was developed. The method was applied to three BEFZs in China—Yili-Tianshan Mountain, San Jiang Plain Wetland and Minshan-Qionglai Mountain—which are located in different geographic environments. The main conclusions are as follows: (1) the reference condition index can reflect differences in the background of conservation capacity among BEFZs examined, allowing comparison of the biodiversity conservation effectiveness between different BEFZs; (2) the conservation effectiveness index is a useful quantitative measure of the biodiversity conservation effectiveness in BEFZs; and (3) application of this method to the three BEFZs indicated that the method can provide a powerful tool for the management of biodiversity conservation in BEFZs at a macroscale in China. Meanwhile, this method can also provide a reference for building strategies for protecting the ecological environments in other countries on a case-by-case basis.