Model Predictive Active Power Control for Optimal Structural Load Equalization in Waked Wind Farms

In this paper, we propose a model predictive active power control (APC) enhanced by the optimal coordination of the structural loadings of wind turbines operating with fully developed wind farm flows that have extensive interactions with the atmospheric boundary layer. In general, the APC problem, that is, distributing a wind farm power reference among the operating wind turbines, does not have a unique solution; this fact can be exploited for structural load alleviation of the individual wind turbines. Therefore, we formulated a constrained optimization problem to simultaneously minimize the wind farm power reference tracking errors and the structural load deviations of the wind turbines from their mean value. Thewind power plant is represented by a dynamic 3D large&ndash;eddy simulation model, whereas the predictive controller employs a simplified, computationally inexpensive model to predict the dynamic power and load responses of the turbines that experience turbulent wind farm flows and wakes. An adjoint approach is an efficient tool used to iteratively compute the gradient of the formulated parameter-varying optimal control problem over a finite prediction horizon. We have discussed the applicability, key features, and computational complexity of the controller by using a wind farm example consisting of 3�4 turbines with different wake interactions for each row. The performance of the proposed adjoint&ndash;based model predictive control for APC was evaluated by measuring power reference tracking errors and the corresponding damage equivalent fatigue loads of the wind turbine towers; we compared our proposed control design with recently published proportional&ndash;integral&ndash;based APC approaches.</p

Monitoring van paraffine-achtige stoffen op Nederlandse stranden en in magen van Noordse Stormvogels

Within the KB-Program System Earth Management 2018 (KB-24-002-036) a pilot study was conducted into options to monitor of paraffin- or palmfat-like substances on Dutch beaches and in stomachs of corpses of beached Northern Fulmars. Such substances are, in part legally, discharged by tanker ships cleaning their tanks at sea.Paraffin was chemically identified by the presence of alkanes in the samples. It remains to be investigated in detail which other mineral oil derivatives may show similar alkane patterns. In the absence of alkanes further analyses were conducted to assess the type of material involved.Samples taken from beaches showed to be paraffin in 30 of 32 analyses (94%). One sample contained palmoil related substances, one sample remained unclear but contained phthalates (eg used as plastic softeners). The materials from bird stomachs proved to be different. Paraffin was only found in 31% of 32 samples. In 41% of the stomachs vegetable fatty substances were demonstrated, usually palm oil related. The remainder of samples had an uncertain mix of vegetable and animal fats. The difference between beaches and bird stomachs may have several backgrounds, including attraction for wildlife, melting points, and biodegradability.Over 20% of fulmars found in the Netherlands has chemical suspect materials in the stomach. Not much is known about potential health impacts. Over the years no clear changes can be detected. Quantities of material ingested are highly variable. Frequency of occurrence may slightly reduce over the more recent years, but there is no statistically significant trend. It would make sense to add records on chemical suspect materials in fulmar stomachs to the existing monitoring of plastics in the framework of OSPAR and the EU Marine Strategy Framework Directive. Clearly chemical analyses of substances encountered on beaches and in birds is additionally recommended

Open Access Solutions for Biodiversity Journals: Don’t Replace One Problem with Another

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