Developing an exhaustive optimal maintenance schedule for offshore wind turbines based on risk-assessment, technical factors and cost-effective evaluation

Abstract

Maintenance scheduling is one of the most challenging issues of offshore wind system, because the maintenance decision may impact greatly to cost-effectiveness. The process of maintenance decision making is confronting with uncertainties, including economic, technical, safety and environmental uncertain that make conventional maintenance optimization insufficient. The conventional maintenance optimization in the existing studies only consider factors related to technical and economic aspects in maintenance optimization. No existing study analyzes the effects of health and safety risks of the technicians and the environmental risks of the maintenance activities under the impacts of the complex weather conditions in the marine environment. The occurrence of environmental and safety risks causes catastrophic consequences, especially in harsh weather condition, that make the conventional maintenance techniques insufficient. This paper proposes an approach to optimize maintenance schedule that is designed to maximize the cost-effectiveness while minimizing the environmental and safety risks. The proposed model utilizes fuzzy probabilities to assess the environmental and safety risks. This paper also presents a mathematical model to derive the optimal individual maintenance schedule and group maintenance schedule for various components by considering a number of impacted factors. The results demonstrated that the number of maintenance activities when considering environmental and safety risks is higher than that without considering environmental and safety risks. For example, the number of maintenance activities with and without considering the environmental and safety risks at the location of 25 km of distance to shore is 75 and 86 activities respectively. The effect of risk-assessment model was more apparent for vulnerable components and was less apparent for the durable components.