Advanced Control Design for Wind Turbines; Part I: Control Design, Implementation, and Initial Tests

The purpose of this report is to give wind turbine engineers information and examples of the design, testing through simulation, field implementation, and field testing of advanced wind turbine controls

Wind Turbine Design Cost and Scaling Model

This model intends to provide projections of the impact on cost from changes in economic indicators such as the Gross Domestic Product and Producer Price Index

Electrical Collection and Transmission Systems for Offshore Wind Power: Preprint

The electrical systems needed for offshore wind farms to collect power from wind turbines--and transmit it to shore--will be a significant cost element of these systems. This paper describes the development of a simplified model of the cost and performance of such systems

Designing and Testing Controls to Mitigate Tower Dynamic Loads in the Controls Advanced Research Turbine: Preprint

This report describes NREL's efforts to design, implement, and test advanced controls for maximizing energy extraction and reducing structural dynamic loads in wind turbines

Modelling wind turbine degradation and maintenance

degradation, inspection and maintenance processes. The model was developed based on the Petri net method that effectively captures the stochastic nature of the dynamic processes through the use of appropriate statistical distributions. The versatility of the method allows the details of the degradation and maintenance operations to be incorporated in the model. In particular, there are dependent deterioration processes between wind turbine subsystems, complex maintenance rules and the incorporation of condition monitoring systems for early failure indication to enable replacement prior to failure. The purposes of the model are to predict the future condition of wind turbine components and to investigate the effect of a specified maintenance strategy. The model outputs are statistics indicating the performance of the wind turbine components; these include the probability of being in different condition states, the expected number of maintenance actions and the average number and duration of system downtime under any maintenance strategy

Plans for Testing the NREL Unsteady Aerodynamics Experiment 10m Diameter HAWT in the NASA Ames Wind Tunnel: Minutes, Conclusions, and Revised Text Matrix from the 1st Science Panel Meeting

Currently, the NREL Unsteady Aerodynamics Experiment (UAE) research turbine is scheduled to enter the NASA Ames 80-ft x 120-ft wind tunnel in early 2000. To prepare for this 3-week test, a Science Panel meeting was convened at the National Wind Technology Center (NWTC) in October 1998. During this meeting, the Science Panel and representatives from the wind energy community provided numerous detailed recommendations regarding test activities and priorities. The Unsteady Aerodynamics team of the NWTC condensed this guidance and drafted a detailed test plan. This test plan represents an attempt to balance diverse recommendations received from the Science Panel meeting, while taking into account multiple constraints imposed by the UAE research turbine, the NASA Ames 80-ft x 120-ft wind tunnel, and other sources. The NREL-NASA Ames wind tunnel tests will primarily be focused on obtaining rotating blade pressure data. NREL has been making these types of measurements since 1987 and has considerable experience in doing so. The purpose of this wind tunnel test is to acquire accurate quantitative aerodynamic and structural measurements, on a wind turbine that is geometrically and dynamically representative of full-scale machines, in an environment free from pronounced inflow anomalies. These data will be exploited to develop and validate enhanced engineering models for designing and analyzing advanced wind energy machines

Technology Improvement Opportunities for Low Wind Speed Turbines and Implications for Cost of Energy Reduction: July 9, 2005 - July 8, 2006

This report analyzes the status of wind energy technology in 2002 and describes the potential for technology advancements to reduce the cost and increase the performance of wind turbines

Tension pneumothorax in a newborn after Cesarean-section delivery -A case report-

Tension pneumothorax in newborns is a rare but life-threatening complication. We encountered a case of a full-term neonate with a breech presentation. An elective cesarean section was scheduled. Immediately after delivery, the newborn was found to be breathless with a heart rate <60/min. During intubation and cardiac massage, the patient's femoral artery and vein were accessed. The infantogram revealed a right side tension pneumothorax. A 22 gauge needle thoracentesis relieved the right side chest pressure and a closed thoracostomy was performed. The severe acidosis was corrected with sodium bicarbonate. The patient was managed in the neonatal intensive care unit, but died from uncorrectable acidosis. We report this case with a review of the relevant literature

Damage measurements on the NWTC direct-drive, Variable-Speed Test Bed

The NWTC (National Wind Technology Center) Variable-Speed Test Bed turbine is a three-bladed, 10-meter, downwind machine that can be run in either fixed-speed or variable-speed mode. In the variable-speed mode, the generator torque is regulated, using a discrete-stepped load bank to maximize the turbine`s power coefficient. At rated power, a second control loop that uses blade pitch to maintain rotor speed essentially as before, i.e., using the load bank to maintain either generator power or (optionally) generator torque. In this paper, the authors will use this turbine to study the effect of variable-speed operation on blade damage. Using time-series data obtained from blade flap and edge strain gauges, the load spectrum for the turbine is developed using rainflow counting techniques. Miner`s rule is then used to determine the damage rates for variable-speed and fixed-speed operation. The results illustrate that the controller algorithm used with this turbine introduces relatively large load cycles into the blade that significantly reduce its service lifetime, while power production is only marginally increased

Analysis of Technology Improvement Opportunities for a 1.5MW Wind Turbine using a Hybrid Stochastic Approach in Life Cycle Assessment

This paper presents an analysis of potential technological advancements for a 1.5 MW wind turbine using a hybrid stochastic method to improve uncertainty estimates of embodied energy and embodied carbon. The analysis is specifically aimed at these two quantities due to the fact that LCA based design decision making is of utmost importance at the concept design stage. In the presented case studies, better results for the baseline turbine were observed compared to turbines with the proposed technological advancements. Embodied carbon and embodied energy results for the baseline turbine show that there is about 85% probability that the turbine manufacturers may have lost the chance to reduce carbon emissions, and 50% probability that they may have lost the chance to reduce the primary energy consumed during its manufacture. The paper also highlights that the adopted methodology can be used to support design decision making and hence is more feasible for LCA studies