Tang Dedong

Simulation for strategy of maximal wind energy capture of doubly fed induction generators

In order to most effectively utilize the wind energy and improve the efficiency of wind generation system, an optimum control strategy of doublyfed induction generators (DFIG) was proposed, which made the system operation for both the maximum wind enemy captured below the rated wind speed. Based on the wind turbine characteristics and basic electromagnetic relationship of DFIG the mathematical models of the stator active power and reactive power of DFIG were derived to fulfill maximal wind energy capture and conversion. A dual-passage excitation fuzzy control strategy based on dynamic synchronous reference frame was applied to control the proposed optimal stator active and reactive power. The operational performances of the wind turbine system with DFIG with wind speed variation were analyzed and compared by using Matlab/Simulink . The results show the correctness and feasibility of the proposed control strategy.

Simulation study of two-order Large Inertia and time-delay system based on active disturbance rejection controller

PID controller can not perform well in two-order large Inertia and time-delay system. ADRC is a new control technique which possesses special advantages for large Inertia and time-delay system. Moreover, ADRC overcomes lots of defects of PID control and improves control performance greatly. Two-tank liquid system — the research object in this paper is a typical two-order large Inertia and time-delay system. In the research an ADRC is designed by using control technique of active disturbance rejection and by comparing with PID controller. Simulation research shows that liquid level control system possesses good rapidity and little overshooting with ADRC and can inhibit strong disturbance. Thus, the research result is of important guidance for engineering of liquid level control.

An approach to on-line moisture content measuring in petroleum products

In view of wide difference dielectric constant between water and petroleum products, an approach to on-line moisture content measuring in petroleum products via the technique of electromagnetic resonance is proposed. In this paper, the principle of moisture content measuring is introduced in detail first, and how to design capacitive sensor and measuring circuit is followed. Finally, how to avoid the influencing factors in the measuring is dwelled upon. An on-line temperature data collecting software has been designed to build temperature error database, which has not only reduced work intensity enormously but also enhanced the measuring precision. Through experiment, it is proved that repetition error of this proposed method is less than 3%.