陸上 風力基礎 缺陷原因 및 共振分析

Abstract

The causes of damage to the connection of the tower and the foundation of a wind turbine were investigated through literature search. In addition, two types of damaged foundation and one type of repaired foundation models were analyzed to provide a good solution to the damage in this thesis. There are two connection types to link the wind turbine tower to the foundation: a anchored type and anchor bolt type. Based on literature search, anchored type may lead to formation with voids between concrete and anchoring flange due to continuous wind turbine vibrations. As for the anchor bolt type, turbine dynamic loads may cause the cracking of mortar grout between the tower bottom flange and concrete foundation. However, damages of anchor bolt type connection occurred less than those of anchored type. Even if the damages occur, those could be repaired easily by means of replacing damaged grout. It is recommended that the anchor bolt type should be applied for linking tower and foundation of a wind turbine. Using Abaqus software application, initial damage model, developed damage model and repaired model for the foundation and the tower of Vestas V90-3MW were analyzed for checking resonance. Eigenvalue analysis was performed, and the results showed that initial damage model and developed damage model approached to rotor resonance frequency bandwidth, lowering tower frequency up to 9.55%. On the other hand, repaired model approached to higher frequency up to 11.23% to avoid rotor resonance bandwidth compared with the developed damage model, recovering the damaged lowered frequency. Therefore, repaired model proposed in this thesis may be a good solution to the damage of foundation connection of a wind turbine.