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고정식 해상풍력발전기의 동적 하중 계산 및 응답해석에 관한 연구

A Study on Dynamic Load Calculation and Response Analysis of a Fixed Offshore Wind Turbine

석상민 (포항공과대학교 일반대학원 풍력특성화협동과정)

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초록 moremore
The utilization of renewable resources such as wind and solar to generate electric power has been receiving considerable attention in recent years. Wind energy in particular has been fast growing and recognized as one of most successful energy sources. Offshore wind farm has a great advantage of ge...
The utilization of renewable resources such as wind and solar to generate electric power has been receiving considerable attention in recent years. Wind energy in particular has been fast growing and recognized as one of most successful energy sources. Offshore wind farm has a great advantage of geographical conditions such that wind speed and quality being more favorable than those in land. The economics of the substructures are different depending on the installation depth. The substructures are divided into fixed type and floating type. Most of the current offshore wind turbine models are fixed types like a monopile and a jacket type. This study is a dynamic load calculation and response analysis of a monopole type and a jacket type offshore wind turbine through a code development. Because the offshore wind turbine system is subjected to wind and wave, current forces, it is necessary to simulate those dynamic loads included. In addition, the marine growth is also considered. The marine growth is known to give adverse effects on the performance of a offshore structure. The offshore wind turbine is subjected to more various irregular and huger loads than the onshore wind turbines and the stability of structures is supported by the piles driven deeply in the subsoil. So it is more important for the offshore structures to consider soil-pile interaction than onshore wind turbines, and for an exact analysis it should be done in soil-pile-superstructure system. Considering soil-pile-superstructure interaction, the spring stiffness between a pile and soil is evaluated by using the coefficient of subgrade reaction, the p-y curve, and the subsoil elastic modulus. Tower and substructure of fixed offshore wind turbine are modeled as multi degree of freedom (MDOF) structure. It is assumed that blades, nacelle are composed of concentrated masses. In order to obtain a dynamic response, Newmark's method is used. The 5MW NREL reference wind turbine models with a monopile type and a jacket type are used for analysis. This analysis is performed in a random offshore environment.
목차 moremore
Abstract ⅰ
목차 ⅲ
그림목차 ⅵ
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Abstract ⅰ
목차 ⅲ
그림목차 ⅵ
표목차 ⅷ
술어 및 약어 ⅸ

Ⅰ. 개요 1
1.1 연구배경 1
1.2 연구내용 및 범위 4

Ⅱ. 해양환경하중 6
2.1 Wind 6
2.1.1 풍속의 고도분포 6
2.1.1.1 대수법칙(Logarithmic Law) 7
2.1.1.2 지수법칙(Power Law) 7
2.1.2 난류강도 8
2.1.3 스펙트럼을 이용한 풍하중 시간이력 변환 8
2.1.4 Thrust Force 13
2.2 Wave 16
2.2.1 파고 스펙트럼 16
2.2.2 스펙트럼을 이용한 파하중 시간이력 변환 18
2.2.3 유체 구조 상호 작용을 고려한 Morison Equation 21
2.2.4 Wave Force on Inclined Members 24
2.3 Marine Growth Effect 26

Ⅲ. 수평재하 말뚝의 해석기법 산정 27
3.1 수평하중을 받는 말뚝의 지지력 산정 방법 27
3.1.1 극한 수평 저항력에 의한 방법 27
3.1.2 허용 변위량에 의한 방법 28
3.2 P-Y 곡선법 28
3.2.1 연약점토 지반에 대한 P-Y 곡선 29
3.2.2 사질토 지반에 대한 P-Y 곡선 31
3.3 무리말뚝 효과 33
3.4 Dynamic P-Y 곡선 34
3.5 Effect of Pile Diameter 35

Ⅳ. 모델링 37
4.1 Monopile type 주요 제원 37
4.1.1 Soil-Pile system 38
4.1.2 Monopile type 모델링 39
4.2 Jacket type 주요 제원 40
4.2.1 Soil-Group Pile system 41
4.2.2 Jacket type 모델링 42
4.3 동적 평형방정식 43
4.4 시간이력해석 45
4.5 직접적분법 45

Ⅴ. Simulation 결과 47
5.1 고유 진동수 및 모드형상 47
5.1.1 Monopile type 결과 47
5.1.2 Jacket type 결과 50
5.2 동적 하중계산 52
5.2.1 Monopile type 결과 53
5.2.2 Jacket type 결과 54
5.2.3 결과정리 및 분석 55
5.3 동적 응답 56
5.3.1 Monopile type 결과 57
5.3.2 Jacket type 결과 58
5.3.2 결과정리 및 분석 59
5.4 결과의 정확성 60


Ⅵ. 결론 62

참고문헌 64

Appendix 68