PO144

Reducing Turbine Mechanical Loads Using Flow Model-Based Wind Farm Controller

Jonas Kazda, Nicolaos Antonio Cutululis
Technical University of Denmark, Roskilde, Denmark

Abstract

Cumulated O&M costs of offshore wind farms are comparable with wind turbine CAPEX of such wind farm. Thus reducing O&M expenses is of similar importance as improving turbine design. In wind farms, wake effects can result in up to 80% higher fatigue loads at downstream wind turbines (Sanderse, 2009) and consequently larger O&M costs. The present work therefore investigates to reduce these loads during the provision of grid balancing services using optimal model-based wind farm control. Wind farm controllers coordinate the operating point of wind turbines in a wind farm in order to achieve a given objective. The investigated objective of the control in this work is to follow a total wind farm power reference while reducing the tower and blade bending moments of the turbines in the wind farm. The wind farm controller is tested on a typical offshore wind farm using the dynamic wind farm simulation tool SimWindFarm ("SimWindFarm Official Website," 2016). The tests show a reduction of loads at downstream turbines, which are likely to reduce O&M need and cost. Moreover, the deviations from the total power reference stay within 5% of the farm's rated power as required by the Danish grid code (Eltra and Elkraft System, 2004). The presented controller can therefore contribute to the reduction of O&M costs while operating the wind farm within given operational limits. Future work shall enhance the controller with more advanced turbine fatigue models in order to further improve the controller's performance.

Method

Wind farm controllers coordinate the operating point of wind turbines in a wind farm in order to achieve a given objective. The investigated objective of the control in this work is to follow a total wind farm power reference while reducing the tower and blade bending moments of the turbines in the wind farm. The developed wind farm controller uses a model-based optimal control approach. The wind farm controller is tested on a typical offshore wind farm using the dynamic wind farm simulation tool SimWindFarm. SimWindFarm allows for the simultaneous simulation of the turbulent hub height flow field in the wind farm, the turbine dynamics and the wind farm control.

Results

The performance of the controller is investigated in different wind conditions. The tests generally show a reduction of loads at downstream turbines, which are likely to reduce O&M need and cost. Moreover, the deviations from the total power reference stay within the 2% error band required by grid codes. The presented controller could therefore contribute to the reduction of O&M costs while operating the wind farm within given operational limits.

Conclusions

This work presents a case study of a newly developed, optimal wind farm controller. The objective of the control is to follow a power reference while reducing the loads of wind turbines in the wind farm. Simulation tests of the controller show a reduction of fatigue loading at downstream turbines. The presented controller could therefore contribute to the reduction of O&M costs of wind farms while operating the farm within given operational limits. Future work shall enhance the controller with more advanced turbine fatigue models in order to further improve the controller's performance.

Objectives

The learning objectives of this work are to

 

References

Sanderse, B. (2009). Aerodynamics of Wind Turbine Wakes: Literature Review. Energy Research Center of the Netherlands (ECN), ECN-E-09-016, Petten, The Netherlands, Tech. Rep, 46.

SimWindFarm Official Website. (2016). Retrieved from http://www.ict-aeolus.eu/SimWindFarm/index.html

Eltra and Elkraft System. (2004). "Grid connection of wind turbines to networks with voltages above 100 kV, Regulation TF 3.2.5"