럼프기법을 이용한 5-MW 해상 풍력발전 시스템의 피로하중 해석

Abstract

The wind turbine technology has advanced to reach to the offshore wind turbine. Differ from onshore wind turbine, large-scale wind farm could be installed and we can have higher power output and better quality of electricity because of less obstacles in offshore sites. However, offshore wind turbines are exposed in the environment of wind, wave, current, the tide and so on. Typically, wave causes large portion of fatigue loads of wind turbine. In standard or guideline, for example IEC, GL, DNV, it says that joint probability distribution of significant wave height, wave period and wind speed should be considered to simulate fatigue analysis. To follow the standard, designers have to run every combination of significant wave height and wave period in each wind speed bin and then apply the probability of occurrence of each sea states to simulate fatigue analysis. Thousands of simulations are needed to exactly follow the design standard and guideline of offshore wind turbine. So, a number of simulations and load cases are significantly increased compared to design onshore wind turbine. In this research, wave period and significant wave height bins are lumped into few load cases by using relationship of damage, wave period and significant wave height. Three sized lumped load cases are simulated and compared to the load cases these are simulated every sea states. The results in mud line, mean sea level, 10m height and blade root are compared. These locations are typical minimum positions for design or certification of wind turbine. As a result, maximum difference is 6.5% in tower mud line and differences of mean sea level, 10m height of tower and blade root are less than 0.5%. Also, the number of load cases is significantly reduced to 1/40.