A few people working at an offshore wind turbine

Work Package 3: Offshore forecast, operation and maintenance

Leader: Anne Karin Magnusson, Met.no

The task aims to integrate all relevant sources of predictive information into well calibrated energy forecasts. The importance of high-resolution atmospheric models and ensembles will be quantified in the context of statistical probabilistic energy forecasting. It is well known that high-resolution atmospheric models in general provide better wind forecasts than global atmospheric models, but the importance to final energy forecast, given that wind forecasts from global models are available, is not well investigated. Similarly, ensembles provide useful information about uncertainty, but their importance in probabilistic energy forecasts is not well documented.

The high mobilisation cost to get personnel offshore to the wind turbine means that the need for frequent maintenance and inspection is to be avoided. Availability for inspection and maintenance will depend highly on service ship used, thus the potential capacity for different service ship designs for different wave climate areas will be determined. Forecasting tools using response calculations will be developed which are expected to give significant improvements compared to standard wave forecasts currently used in marine operations. Risk reduction is achieved by evaluating equipment sparing and redundancy. Ensuring machinery uptime is critical to maximise availability and production. The purpose of condition monitoring is to maximise the Life Time Profit of the plant. Implementing condition monitoring allows maintenance and repair activities to be scheduled, causing the shortest possible downtime. Minimising production losses and avoiding secondary damage incurred through the failure of vital parts secures considerable economic benefits.

A key issue in describing the energy production is the calculation of the wake losses of the wind farms. Future wind farms in the Nordic countries are foreseen to be large and subject to cold climate (which will result in icing of the wind turbine blades). Therefore a special interest will be given to how icing affects the production. Large wind farms are shown to give flow effects on the mesoscale affecting the energy production of the wind farm. Mesoscale effects together with effects of the atmospheric stability are presently either not described or poorly described in industry standard wake models and the CFD models used to represent the background flow. Here stability effects and mesoscale effects in the energy production calculations will be assessed using mesoscale meteorological models.