Ship collision impact on the structural load of an offshore wind turbine

When a maintenance and operations ship is berthing,there is a chance the ship may collide into the wind turbine.When these ships collide into wind turbine structures,this can result in significant changes to the foundation and structure of the wind turbine.In this paper,the structural load of a 4 MW offshore wind turbine was analyzed during a collision with an operations and maintenance ship.The variations in the wind speeds on hub height,waves,and the sea currents were measured.The dynamic simulation of the wind turbine was carried out using the test data as the input parameters.As a result,the load condition of the turbine without a collision was obtained.Finally,the measured turbine load was compared with the simulation results.This study shows that the collision of the operation and the maintenance ship increases the bending moments at the tower’s bottom and the blade’s roots.

An Improved SVM Based Wind Turbine Multi-fault Detection Method

A fault detection method bases on wind turbines(WTs)supervisory control and data acquisition(SCADA)is proposed,principal component analysis(PCA)was used to reduce the dimension of target features to 1-D,so that PCA output 1-D data can be used as label of support vector machine(SVM).Thus on the premise of not losing the prediction correctness,one model can detect the fault of 2 to 4 features,largely reduce the complexity of model building.Different experiments are present to show the effectiveness of the proposed method.

Ensemble Learning-Based Wind Turbine Fault Prediction Method with Adaptive Feature Selection

In this paper we present a wind turbine (WT) fault detection method based on ensemble learning, WT supervisory control and data acquisition (SCADA) is used for model building. In feature selection process, random forest algorithm is applied to get the feature importances,this is much convenient compared with general feature selection by experience, also more accurate result is obtain. In model building,SVM based bagging algorithm is used, compared to individual SVM,out method is much faster and again with a better result.

Study on grid adaptability testing methodology for wind turbines

The use of wind power has grown rapidly in recent years.Wind power is a clean source of energy,but can have negative impacts on the distribution grid.The influence of large-scale wind power integration on the safe and stable operation of a power system cannot be ignored.It is necessary and urgent to achieve grid adaptability for wind turbines in China.Using a 35 kV/6 MVA grid simulator,the performance of a grid is investigated by simulation.Typical grid disturbances such as voltage deviation,frequency fluctuation,voltage unbalance,and distortion can be simulated.A grid adaptability testing methodology was developed and applied to a doubly fed wind turbine with a focus on analyzing real test data to ascertain its three-phase voltage unbalance adaptability,which was successfully demonstrated.The methodology can also be used to guide other grid adaptability tests.

The effect of hydrogen on the recombination of Frenkel pair in tungsten： A theoretical insight

Tungsten (W), with its primary advantages, is considered as the most promising candidate for plasma facing materials (PFMs) for the next generation of fusion devices such as ITER. However, continuous bombardment with 14.1 MeV neutron introduces Frenkel defects as the primary damage in W [1]. The Frenkel defects, composed of self-interstitial atoms (SIAs) and vacancies, can develop to extended defects such as voids and interstitial clusters, resulting in hardening, swelling and embrittlement of W, thus degrading the properties of W [2]. The recombination of SIAs and vacancies is an effective way to reduce the Frenkel defects in bulk W, which enhances the radiation resistance of W based on recent theoretical calculations [3,4]. The moving of the SIA to the vacancy could finish the recombination process through instantaneous or thermally activated way [3]. The instantaneous recombination region is an ellipse with the semi-minor axis of 5.4 ? and semi-major axis of 18 ? according to the molecular dynamics calculation [4].