Fault condition effects on the dynamic response of V-shaped offshore wind turbine

Madjid Karimirad,Constantine Michailides

doi:10.1007/s00773-018-0529-3

Madjid Karimirad, Constantine Michailides

Open Access

https://doi.org/10.1007/s00773-018-0529-3

Copy DOI

Abstract

Offshore wind is an extensive renewable energy resource appropriate for fulfilling the increasing energy needs and increasing the security of energy supply. The issues related to the design of the support structure, installation, grid connection, operation, and maintenance in normal and fault conditions significantly influence the levelized cost of the produced energy. The feasibility of different concepts should be numerically calculated and assessed for all aforementioned issues. In this paper, the dynamic response of the V-shaped semisubmersible under different possible fault conditions is examined. Different response quantities of the floating wind turbine are compared for the case that the system operates under operational and fault conditions. The response quantities include motions of the platform in all six rigid-body degrees of freedom, mooring line tension, tower base-bending moment, and functionality of the wind turbine. A numerical model accounting for fully coupled dynamic analysis of the offshore wind turbine under different fault conditions has been developed. It is found that for the V-shaped semisubmersible, the mooring line tension is significantly affected by different fault conditions compared to the rest examined response quantities; the maximum value of the tension of the mooring lines is increased by a factor of 1.6 due to fault conditions. Among the different fault conditions, shutdown case seems to have the largest influence on the functionality and responses of the V-shaped floating wind turbine. For emergency shutdown fault conditions, backlash occurs that results in large variation of tower-bending moment.

Highlights

Offshore wind turbines are subjected to a variety of loads
Fault conditions result in a 1.6 times increase in the maximum tension of the mooring lines; this factor should be considered for addressing the structural integrity of the mooring system of the V-shaped semisubmersible
Fault conditions may result in significant effects on the structural responses of such structures due to induced transient loads

Summary

Introduction

Detailed analysis of different conditions (operational, fault, and extreme) is necessary in order we to understand the performance of different floating wind turbines and to recognize critical circumstances caused by the operation of the turbine in normal, survival, or fault conditions The latter is the focus of this paper; the present paper is a further study based on. The response quantities of different components of the V-shaped semisubmersible are compared for the case that the offshore wind turbine operates under operational and fault conditions. Fault conditions result in a 1.6 times increase in the maximum tension of the mooring lines; this factor should be considered for addressing the structural integrity of the mooring system of the V-shaped semisubmersible. Time-domain dynamic analysis is applied to investigate the responses of the V-shaped floating wind turbine under the action of wind and wave loads for the examined fault conditions. The turbulent wind field is generated with the use of HAWC2 [11] and is used as input to SIMA

Description of quantity

Fault case

Ratio of maxima

Findings

Conclusions