Wind turbine tower has a very important role in wind turbine system as one of the renewable energy that has been attracting attention worldwide recently. Due to the growth of wind power market, advance and development of offshore wind system and getting huger capacity is inevitable. As a result, the vibration is generated at wind turbine tower by receiving constantly dynamic loads such as wind load and wave load. Among these dynamic loads, the mechanical load caused by the rotation of the blade is able to make relatively periodic load to the wind turbine tower. So natural frequency of the wind turbine tower should be designed to avoid the rotation frequency of the rotor according to the design criteria to avoid resonance. Currently research of the wind turbine tower, the precise research does not be carried out because of simplifying the structure of the other upper and lower. In this study, the effect of blade modeling differences are to be analyzed in natural frequency of wind turbine tower.

Internally confined hollow reinforced concrete (ICH RC) wind power towers were designed for various turbines sizes. Their cross sections were designed to have equal diameters to those of general steel wind power towers corresponding 3.6MW and 5.0MW turbines. And also, the sections with the average diameter of 3.6MW and 5.0MW turbines were designed. For the determined diameters, several cross sections were designed for various hollow ratios. The designed sections were set to have almost equal longitudinal reinforcement ratios. The performance analyses for the designed cross sections were carried out and the analysis results showed that the ICH RC wind power tower had enough strength for the required design loads.

Natural frequency characteristic of Wind turbine tower is important for designing of tower due to guarantee of structural safety of tower. In GL specification, natural frequency of tower should be designed by consideration of blade rotational frequency. Natural frequency characteristic of tower could be changed by mass ratio of RNA-tower, modeling method of blade and angle of blade in idling condition. In this research, natural frequency of tower is analysed by ABAQUS and compared it result according to tower dimension.

An ICH RC (internally confined hollow reinforced concrete) tower for supporting 5.0MW wind turbine was developed and its standard sections were designed. It was found that ICH RC wind tower is satisfied with maximum 200% bigger moment which is required for pre-existing steel tower. Also, the results from the FAST showed that 5.0MW turbine can be normally operated with the ICH RC tower.

A standard design section of a FRP DSCT wind power tower supporting 3MW was suggested and designed through AutoDSCT and CoWiTA programs. The thicknesses of the FRP tubes were optimized and by using the parameters of designed tower, the performance of the new type wind tower was evaluated via FAST program.

대형화되고 있는 풍력발전 터빈에 대응하여 내부구속 중공 철근콘크리트(ICH RC; Internally Confined Hollow Reinforced Concrete) 구조를 적용한 풍력타워 제안되고 연구되고 있다. 이에 기존의 3.6MW 터빈과 5.0MW 터빈에 대응하는 ICH RC 풍력타워 단면이 설계된바 있다. 하지만, 풍력발전 터빈은 큰 질량을 갖는데 비해 타워는 세장비가 매우 크기 때문에, 풍하중 등의 횡하중이 작용할 때 발생하는 변위가 증가함에 따라, 터빈의 자중에 의한 대변위 효과에 따라 실제 횡력에 저항할 수 있는 모멘트 저항성능은 감소한다. 따라서 안전한 풍력발전 타워의 설계를 위해서는 대변위 효과를 고려하여 실제 횡력에 저항할 수 있는 타워의 모멘트 성능을 계산하는 것이 중요하다. 이에 본 연구에서는 기존 설계된 단면에 대해 터빈 자중에 의한 대변위 효과를 고려하여 모멘트-횡변위 해석을 수행하였다. 해석결과, 터빈 자중에 의한 대변위 효과로 인하여 풍력타워의 실 모멘트 저항 성능 감소분이 상당하며, 안전한 풍력타워의 설계를 위해서는 대변위 효과가 반드시 고려되어야 함을 알 수 있었다.