ABSTRACT

The influence of the accuracy of the weather forecast on the availability and production losses for a given maintenance policy are investigated in this paper. This is done by varying the look ahead time, with accurate weather forecast, of a simulation model. The results show that for the maintenance policy that was chosen for the model, the availability of the wind farm decreases while production losses increase with a longer look ahead time. This is caused, since in the given policy, maintenance actions are not started, if the weather forecast predicts a storm during the time needed for the maintenance action. This also demonstrates the importance of a proper maintenance strategy.

INTRODUCTION

Offshore wind energy is still significantly more expensive than onshore wind energy and not yet economically profitable without governmental subsidies. One of the driving factors is the cost of operations and maintenance in offshore wind farms. Since corrective maintenance causes longer down-times and therefore higher cost, reducing the amount of corrective maintenance and optimizing the scheduling of the corrective maintenance tasks are in the focus of current research. To tackle the problem of optimising the scheduling of corrective maintenance, several models to simulate the scheduling of corrective maintenance have been developed by Douard et al. (2012), Scheu et al. (2012), Dinwoodie et al. (2013), Hofmann and Sperstad (2013), Endrerud et al. (2014) and Endrerud and Liyanage (2015).

These models include different aspects of the maintenance scheduling, such as wind turbine and component failures, spare part and crew gathering times, vessel activation times, wind farm access, repair operations and weather conditions, like wind speed and wave height. All of these influencing factors are subject to uncertainties. However, most models assume constant values for one or more of them. A sensitivity analysis by Martin et al. (2016), using one of the models, has shown that the most important factors influencing the operations and maintenance cost and wind farm availability are access and repair costs as well as failure rates. The influence of the variation in repair times on the maintenance delays due to sea state, the availability and the production losses have been investigated by Seyr and Muskulus (2016a) using an analytical model for the delay from Feuchtwang and Infield (2013). Variations in the repair times and their influence on the availability and production losses were investigated by Seyr and Muskulus (2016b) using the simulation model from Scheu et al. (2012).

You can access this article if you purchase or spend a download.