석션 버켓 지지구조 해상 풍력발전기의 고유진동수 예측과 구조물 건전성 감시 시스템을 이용한 고유진동수 관찰 = Prediction of Natural Frequency of an Offshore Wind Turbine with a Support Structure with Suction Buckets and Observation by Structural Health Monitoring System

다국어 초록 (Multilingual Abstract)

As the reliability of a tripod support structure with suction buckets should be evaluated by avoiding resonance, an efficient method to predict natural frequency, which is also known as an effective tool to show the existence of damage in wind turbines, is suggested. The whole structure is modeled by beam elements, while a nacelle with blades is considered as a mass. A boundary condition of the suction buckets is described by a serial combination of stiffness elements for soil and a connecting part of a suction bucket. Then, an effective structural health monitoring (SHM) system is developed to validate the proposed modelling method. Accelerometers, strain gauge and various sensors for measurement of sea environment are installed in proper locations, and measured natural frequency is extracted by measured bending strain. It is validated that the measured natural frequency is the almost the same as the predicted one, with an error rate below 1%, and the natural frequency has sufficient margin to major excitation frequencies such as 1P and 3P. Also, it is observed that the measured natural frequency is constant for 3 months.

참고문헌 (Reference)

1 유정수, "해상풍력터빈의 고유진동수 예측을 위한 지반에 인입된 파일의 탄성지지보 모델 기반 수평 거동 해석" 한국음향학회 35 (35): 261-271, 2016

2 서윤호, "석션 버켓 지지구조를 포함하는 해상 풍력발전기 고유진동수 추정을 위한 모형화" 한국풍력에너지학회 7 (7): 29-34, 2016

3 R. Andrew Swartz, "Structural monitoring of wind turbines using wireless sensor networks" 국제구조공학회 6 (6): 183-196, 2010

4 Faulkner, P., "Structural Health Monitoring Systems on Offshore Wind Turbine Structures" 2013

5 Rohrmann, R., "Results from Monitoring and Assessment of Offshore Wind Turbines" 2011

6 Andersen, L., "Natural Frequencies of Wind Turbines on Monopile Foundations in Clayey soils—A Probabilistic Approach" 43 : 1-11, 2012

7 Liingaard, M., "Impedance of Flexible Suction Caissons" 36 : 2249-2271, 2007

8 Wolf, J., "Foundation Vibration Analysis: A Strength-of-Materials Approach" Elsevier 2004

9 Houlsby, G., "Field trials of suction caissons in sand for offshore wind turbine foundations" 56 (56): 3-10, 2006

10 Houlsby, G., "Field trials of suction caissons in clay for offshore wind turbine foundations" 55 (55): 287-296, 2005

11 Ryu, M. S., "Design, Construction and Installation of Offshore Wind Turbine with Tripod Suction Pile Foundation" 2017

12 Damgaard, M., "Cross-wind Modal Properties of Offshore Wind Turbines Identified by Full Scale Testing" 113 : 94-108, 2013

13 Oh, K. Y., "A review of foundations of offshore wind energy convertors:Current status and future perspectives" 88 : 16-36, 2018