Wind Turbine Installation Vessel Research Articles

다양한 형상의 Jack-up Leg에 대한 해양 동역학적 수치해석

In this study, the hydrodynamic characteristics of various types of jack-up legs for a wind turbine installation vessel were analyzed. Using the modified Morison equation, the wave and current excit ation forces on the jack-up legs were calculated. A modal analysis was performed to predict the dynamic responses for various types of jack-up legs. The Newmark-beta time integration scheme was used to solve the equation of motion in waves in the time domain. The maximum displacement and maximum bending stress were computed for four different types of legs, and their results were compared to select an optimum leg type. Finally, a six-leg jack-up rig with the selected optimal legs was modeled, and its natural period and hydrodynamic behaviors were evaluated.

Structural Strength Analysis of Main Crane Pedestal of the Jack-Up Wind Turbine Installation Vessel

The jack-up wind turbine installation vessel is a special kind of vessel for building the offshore wind power farm. The main crane pedestal, which is the supporting structure of the crane on the main deck of the vessel, is always under high level loads when the ship is in operation condition. In this paper, the structural strength analysis of main crane pedestal of the jack-up wind turbine installation vessel was presented. The direct calculated method was used to evaluate the strength of the main crane pedestal. The FE model of main crane pedestal was established with refined mesh, and the adjoining hull structure was also modeled to provide accurate boundary condition. Considering the permanent loads, variable loads (crane loads) and wind loads on the pedestal, the load combinations were defined for the ultimate limit state for every 45 degree. The deformation and stress of the pedestal and the hull structures were calculated and checked. The results showed that all stress results were within the maximum allowable stresses. The critical areas are often located at the link region of hull and pedestal.

해상풍력발전 설치를 위한 jack-up rig 작업 시 연약지반에 발생하는 지반침하에 관한 연구

Abstract: With concern for new renewable energy sources rising, the offshore wind turbine energy marketis growing. In order to install offshore wind turbines safely in a harsh environment, jack-up rigs need to beused. Recently, a WTIV(Wind Turbine Installation Vessel), which has a self-propelling system, was developed to replace traditional jack-up rigs. Since the jack-up rig works at 60 meters of depth in offshoreand the seafloor is composed mostly of soft clay and sand, it is necessary to conduct a stability examination for ground subsidence before using it. This study conducts an improved numerical analysis of the effect of jack-up rig loading on the soft ground by using FLAC3D considering consolidation theory. This includes analyzing the amount of subsidence when applying different cases of surchargings. It can beconcluded that the mid-loading method has an advantage as regards clay layers and the pre-loading methodhas an advantage as regards sand layers. Key words: Jack-up, Offshore wind turbine, Ground subsidence, Numerical analysis

Research on Automatic Balance Control of Self-Elevating Offshore Wind Turbine Installation Vessel

Automatic balance control in the jacking process of the self-elevating offshore wind turbine installation vessel is the guarantee of the vessel’s safe operations. The automatic balance method in the movement of the wind turbine installation vessel is analyzed, and a leveling scheme by the proportion reversing valves as the actuator is proposed. Then, the leveling principle of heavy platform is studied; an automatic balance strategy which is the combination of displacement leveling strategy and angle leveling strategy is given. Also, an automatic balance control system of wind turbine installation vessel which is based on PLC and PROFIBUS-DP fieldbus is established. PLC is as the main controller. Fieldbus adopted to realize data transmission between master and slave. And the balance procedure based on PID is designed. The research shows that the control system has good control effect such as fast response, high precision and good stability.