Current Issue : October - December Volume : 2017 Issue Number : 4 Articles : 5 Articles
In this paper, a stand-alone hybrid microgrid consisting of wind turbines,\nphotovoltaic (PV) arrays and storage battery banks is developed for use in\nQinghai Province, China. With the help of Software Homer and Matlab, different\nvariables such as annual average wind speed, annual average load demand,\nand annual capacity shortage are considered. The net present value is\nthen used during an entire project lifetime for the optimization solution....
To optimally plan maintenance of wind turbine blades, knowledge of the degradation\nprocesses and the remaining useful life is essential. In this paper, a method is proposed for calibration\nof a Markov deterioration model based on past inspection data for a range of blades, and updating\nof the model for a specific wind turbine blade, whenever information is available from inspections\nand/or condition monitoring. Dynamic Bayesian networks are used to obtain probabilities of\ninspection outcomes for a maximum likelihood estimation of the transition probabilities in the\nMarkov model, and are used again when updating the model for a specific blade using observations.\nThe method is illustrated using indicative data from a database containing data from inspections of\nwind turbine blades....
The effects of two types of flow control devices, vortex generators (VGs) and Gurney\nflaps (GFs), on the power output performance of a multi-megawatt horizontal axis wind turbine\nis presented. To that end, an improved blade element momentum (BEM)-based solver has been\ndeveloped and BEM-based computations have been carried out on the National Renewable Energy\nLaboratory (NREL) 5 MWbaseline wind turbine. The results obtained from the clean wind turbine\nare compared with the ones obtained from the wind turbine equipped with the flow control devices.\nA significant increase in the average wind turbine power output has been found for all of the\nflow control device configurations and for the wind speed realizations studied in the present work.\nFurthermore, a best configuration case is proposed which has the largest increase of the average\npower output. In that case, increments on the average power output of 10.4% and 3.5% have been\nfound at two different wind speed realizations. The thrust force and bending moment in the root\nof the blade have also been determined and compared with the values of the clean wind turbine.\nA residual increase in the bending moment of less than 1% has been found....
Wind energy generated from the wake of moving cars has a large energy potential that\nhas not yet been utilized. In this study, a vertical axis wind turbine (VAWT) was used to recover\nenergy from the wakes of moving cars. The turbine was designed to be planted by the side of the car\nlane and driven by the wake produced by the car. Transient computational fluid dynamics (CFD)\nsimulations were performed to evaluate the performance of the VAWT. The influence of two main\nfactors on the performance of the VAWT, the velocity of the car and the gap between the car and\nthe rotor, were studied. The simulations confirmed the feasibility of this plan, and in the tested\ncases, the VAWT was able to generate a maximum energy output of 100.49 J from the wake of a car.\nThe results also showed that the performance of the VAWT decreased with the velocity of the car,\nand the increased gap between the car and the VAWT....
The gearbox is one of the key components in wind turbines. Gearbox fault signals are\nusually nonstationary and highly contaminated with noise. The presence of amplitude-modulated\nand frequency-modulated (AM-FM) characteristics compound the difficulty of precise fault diagnosis\nof wind turbines, therefore, it is crucial to develop an effective fault diagnosis method for such\nequipment. This paper presents an improved diagnosis method for wind turbines via the combination\nof synchrosqueezing transform and local mean decomposition. Compared to the conventional\ntime-frequency analysis techniques, the improved method which is performed in non-real-time can\neffectively reduce the noise pollution of the signals and preserve the signal characteristics, and hence\nis suitable for the analysis of nonstationary signals with high noise. This method is further validated\nby simulated signals and practical vibration data measured from a 1.5 MW wind turbine. The results\nconfirm that the proposed method can simultaneously control the noise and increase the accuracy of\ntime-frequency representation....
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