Abstract

Wind energy takes first place in many countries among other renewable energy. However, the power quality problems such as nonlinear and unbalanced loads, unbalanced grid, can increase the mechanical vibrations as well as the risk of overheating in Wind Energy Conversion System (WECS). Therefore, the objective of this work is the use of robust flying capacitor converter in order to enhance the WECS efficiency by minimizing mechanical vibrations and reducing thermal stress with minimum voltage stress of power switches. To this end, this paper proposes a WECS based on doubly fed induction generator (DFIG) with the stator connected directly to non-ideal power grid, grid side converter (GSC) with flying capacitor topology and robust input output linearization control used to regulate the dc side capacitor voltage and also compensate the current harmonics in power grid in order to avoid excessive heating and mechanical vibrations in WECS. Simulation using MATLAB demonstrate that the proposed approach improves the power quality by reducing the total harmonic distortion (THD) of grid current to a value which satisfies the limits of IEEE standard, and allows the 8 KW DFIG to operate with reduced mechanical vibration and minimum heating stress in addition to the generation of power.

摘要

在其他可再生能源中，风能在许多国家中名列前茅。然而，非线性和不平衡负载、电网不平衡等电能质量问题会增加风能转换系统（WECS）的机械振动以及过热风险。因此，这项工作的目标是使用稳健的飞跨电容器转换器，通过最大限度地减少机械振动和减少热应力以及功率开关的最小电压应力来提高 WECS 效率。为此，本文提出了一种基于双馈感应发电机 (DFIG) 的 WECS，定子直接连接到非理想电网，具有飞跨电容器拓扑结构和稳健的输入输出线性化控制的网侧转换器 (GSC) 用于调节直流侧电容器电压并补偿电网中的电流谐波，以避免 WECS 中的过度加热和机械振动。使用 MATLAB 进行的仿真表明，所提出的方法通过将电网电流的总谐波失真 (THD) 降低到满足 IEEE 标准限制的值来改善电能质量，并允许 8 KW DFIG 在减少机械振动和最小发热的情况下运行除了发电之外的压力。