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A platform for research: civil engineering, architecture and urbanism
Assessment of a rotor blade extension retrofit as an alternative to the lifetime extension of wind turbines
Wind farm operators are motivated to reduce the levelized cost of energy (LCoE) of their wind turbines. Occasionally, the fatigue budget is not fully utilized during the design lifetime of a turbine. The LCoE can be decreased when the energy yield is increased. To achieve this, the lifetime of the turbine is extended until the fatigue budget is exhausted. Alternatively, a rotor blade extension (RBE) is an option to increase the energy yield of an operating wind turbine. An RBE extends the blade length and increases the rotor diameter and thus the swept area of the rotor. The loads on the turbine, however, are increased by the RBE as well. Higher loads reduce the fatigue budget of a turbine. This study investigates whether the use of an RBE is advantageous compared with the lifetime extension. Loads can be part-wise decreased by the controller, i.e., by modification of the pitch or lowering the cut-out wind speed. The lead-lag loads on the existing blade, however, increase due to added tip mass of the RBE. Because lead-lag loads are the design-driving loads for blades, this study focuses on the fatigue life reduction of an extended 34 m blade of a 1.5 MW turbine. To this end, the blade length was increased parametrically. As a case study, a commercial turbine sited in Iselersheim, Northern Germany, was chosen for the assessment of the life time extension (LTE). Aero-servo-elastic multi-body load simulations were conducted. Furthermore, a structural analysis of the most critical structural detail, i.e., the trailing edge bond line, was conducted. The increase in annual energy production is compared to the decrease in the fatigue budget for different lengths of the RBE. The LTE assessment revealed that the life time of the turbine was dominated by a different component than the blade, i.e., the shaft. The possible LTE of the turbine equals 8.7 years. Hence, the blade fatigue loads may be increased until the fatigue budgets of the blade and the critical components are equalized without reducing the total life time of the turbine. Using this surplus fatigue budget in the blade, the 34 m blade can be extended by 0.8 m. The increase in blade length leads to an increase in annual energy production (AEP) of 2.3 %. Hence, the RBE is especially viable when installed early in the turbine life. ; We acknowledge the support of the German Federal Ministry for Economic Affairs and Energy (BMWi) within the SmartBlades2 project (grant agreement No. 0324032B) and the P. E. Concepts GmbH.
Assessment of a rotor blade extension retrofit as an alternative to the lifetime extension of wind turbines
Wind farm operators are motivated to reduce the levelized cost of energy (LCoE) of their wind turbines. Occasionally, the fatigue budget is not fully utilized during the design lifetime of a turbine. The LCoE can be decreased when the energy yield is increased. To achieve this, the lifetime of the turbine is extended until the fatigue budget is exhausted. Alternatively, a rotor blade extension (RBE) is an option to increase the energy yield of an operating wind turbine. An RBE extends the blade length and increases the rotor diameter and thus the swept area of the rotor. The loads on the turbine, however, are increased by the RBE as well. Higher loads reduce the fatigue budget of a turbine. This study investigates whether the use of an RBE is advantageous compared with the lifetime extension. Loads can be part-wise decreased by the controller, i.e., by modification of the pitch or lowering the cut-out wind speed. The lead-lag loads on the existing blade, however, increase due to added tip mass of the RBE. Because lead-lag loads are the design-driving loads for blades, this study focuses on the fatigue life reduction of an extended 34 m blade of a 1.5 MW turbine. To this end, the blade length was increased parametrically. As a case study, a commercial turbine sited in Iselersheim, Northern Germany, was chosen for the assessment of the life time extension (LTE). Aero-servo-elastic multi-body load simulations were conducted. Furthermore, a structural analysis of the most critical structural detail, i.e., the trailing edge bond line, was conducted. The increase in annual energy production is compared to the decrease in the fatigue budget for different lengths of the RBE. The LTE assessment revealed that the life time of the turbine was dominated by a different component than the blade, i.e., the shaft. The possible LTE of the turbine equals 8.7 years. Hence, the blade fatigue loads may be increased until the fatigue budgets of the blade and the critical components are equalized without reducing the total life time of the turbine. Using this surplus fatigue budget in the blade, the 34 m blade can be extended by 0.8 m. The increase in blade length leads to an increase in annual energy production (AEP) of 2.3 %. Hence, the RBE is especially viable when installed early in the turbine life. ; We acknowledge the support of the German Federal Ministry for Economic Affairs and Energy (BMWi) within the SmartBlades2 project (grant agreement No. 0324032B) and the P. E. Concepts GmbH.
Assessment of a rotor blade extension retrofit as an alternative to the lifetime extension of wind turbines
Rosemeier, Malo (author) / Saathoff, Matthias (author) / Antoniou, Alexandros (author)
2019-06-18
Conference paper
Electronic Resource
English
DDC:
690
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