Predictive control of wind turbines by considering wind speed forecasting techniques

A wind turbine system is operated such that the points of wind rotor curve and electrical generator curve coincide. In order to obtain maximum power output of a wind turbine generator system, it is necessary to drive the wind turbine at an optimal rotor speed for a particular wind speed. A Maximum Power Point Tracking (MPPT) controller is used for this purpose. In fixed-pitch variable-speed wind turbines, wind-rotor parameters are fixed and the restoring torque of the generator needs to be adjusted to maintain optimum rotor speed at a particular wind speed for optimum power output. In turbulent wind environment, control of variable-speed fixed-pitch wind turbine systems to continuously operate at the maximum power points becomes difficult due to fluctuation of wind speeds. In this paper, wind speed forecasting techniques will be considered for predictive optimum control system of wind turbines

Massachusetts Offshore Wind Future Cost Study

The Special Initiative on Offshore Wind is an independent project at the University of Delaware's College of Earth, Ocean and Environment that supports the advancement of offshore wind as part of a comprehensive solution to the most pressing energy problems facing the United States.  The Special Initiative on Offshore Wind provides expertise, analysis, information sharing, and strategic partnership with industry, advocacy and government stakeholders to build understanding and drive the deployment of offshore wind

The environment of the wind-wind collision region of η\eta Carinae

$\eta$ Carinae is a colliding wind binary hosting two of the most massive stars and featuring the strongest wind collision mechanical luminosity. The wind collision region of this system is detected in X-rays and $\gamma$-rays and offers a unique laboratory for the study of particle acceleration and wind magneto-hydrodynamics. Our main goal is to use X-ray observations of $\eta$ Carinae around periastron to constrain the wind collision zone geometry and understand the reasons for its variability. We analysed 10 Nuclear Spectroscopic Telescope Array (NuSTAR) observations, which were obtained around the 2014 periastron. The NuSTAR array monitored the source from 3 to 30 keV, which allowed us to grasp the continuum and absorption parameters with very good accuracy. We were able to identify several physical components and probe their variability. The X-ray flux varied in a similar way as observed during previous periastrons and largely as expected if generated in the wind collision region. The flux detected within ~10 days of periastron is lower than expected, suggesting a partial disruption of the central region of the wind collision zone. The Fe K$\alpha$ line is likely broadened by the electrons heated along the complex shock fronts. The variability of its equivalent width indicates that the fluorescence region has a complex geometry and that the source obscuration varies quickly with the line of sight.Comment: to be published in A&A, 7 pages, 9 figure

Analysis of Dynamic Behaviour and Power Generation of a Wind-tidal System for Marine Environment

This work presents the analysis of dynamic behaviour and power generation of a wind-tidal hybrid system. Mathematical models and system design approach were used to investigate the feasibility, reliability and economic impact of the system. From the system design analysis carried out, by harnessing the tidal energy with wind energy in marine environment, the total power generated (approximately 180KW) by the hybrid power system showed a significant improvement over a wind turbine system which only generates a maximum power of 25KW at the rotor diameter as reported in literature. The effects of aerodynamics and hydrodynamics forces on the structure were investigated through the analysis of dynamic behaviour of the system under different loads and at various sites in the marine environment. The stability and the optimum turbine design were found to depend on the wind and tidal speed distribution of the specific site in the environment. The long term benefit of this work is aimed at meeting the energy needs of coastal dwellers by implementing the hybrid power system. Also, the gridless system could be used to generate power for both large and small scale industries in the marine environmen

Solar-wind predictions for the Parker Solar Probe orbit

The scope of this study is to model the solar-wind environment for the Parker Solar Probe's unprecedented distances down to 9.86 Rs in its mission phase during 2018-2025. The study is performed within the CGAUSS project which is the German contribution to the PSP mission as part of the WISPR imager on PSP. We present an empirical solar-wind model for the inner heliosphere which is derived from OMNI and Helios data. The sunspot number (SSN) and its predictions are used to derive dependencies of solar-wind parameters on solar activity and to forecast them for the PSP mission. The frequency distributions for the solar-wind key parameters magnetic field strength, proton velocity, density, and temperature, are represented by lognormal functions, considering the velocity distribution's bi-componental shape. Functional relations to the SSN are compiled using OMNI data and based on data from both Helios probes, the parameters' frequency distributions are fitted with respect to solar distance. Thus, an empirical solar-wind model for the inner heliosphere is derived, accounting for solar activity and solar distance. The inclusion of SSN predictions and the extrapolation down to PSP's perihelion region enables us to estimate the solar-wind environment for PSP's planned trajectory during its mission duration. This empirical model yields estimated solar-wind values for PSP's 1st perihelion in 2018 at 0.16 au: 87 nT, 340 km s-1, 214 cm-3 and 503000 K. The estimates for PSP's first closest perihelion, occurring in 2024 at 0.046 au, are 943 nT, 290 km s-1, 2951 cm-3, and 1930000 K. Since the modeled velocity and temperature values below approximately 20 Rs appear overestimated in comparison with existing observations, this suggests that PSP will directly measure solar-wind acceleration and heating processes below 20 Rs as planned.Comment: 14 pages, 14 figures, 4 tables, accepted for publication in A&

The Space Environment and Atmospheric Joule Heating of the Habitable Zone Exoplanet TOI700-d

We investigate the space environment conditions near the Earth-size planet TOI~700~d using a set of numerical models for the stellar corona and wind, the planetary magnetosphere, and the planetary ionosphere. We drive our simulations using a scaled-down stellar input and a scaled-up solar input in order to obtain two independent solutions. We find that for the particular parameters used in our study, the stellar wind conditions near the planet are not very extreme -- slightly stronger than that near the Earth in terms of the stellar wind ram pressure and the intensity of the interplanetary magnetic field. Thus, the space environment near TOI700-d may not be extremely harmful to the planetary atmosphere, assuming the planet resembles the Earth. Nevertheless, we stress that the stellar input parameters and the actual planetary parameters are unconstrained, and different parameters may result in a much greater effect on the atmosphere of TOI700-d. Finally, we compare our results to solar wind measurements in the solar system and stress that modest stellar wind conditions may not guarantee atmospheric retention of exoplanets.Comment: accepted to Ap

Interaction of Infall and Winds in Young Stellar Objects

The interaction of a stellar or disk wind with a collapsing environment holds promise for explaining a variety of outflow phenomena observed around young stars. In this paper we present the first simulations of these interactions. The focus here is on exploring how ram pressure balance between wind and ambient gas and post-shock cooling affects the shape of the resulting outflows. In our models we explore the role of ram pressure and cooling by holding the wind speed constant and adjusting the ratio of the inflow mass flux to the wind mass flux (Mdot_a/Mdot_w) Assuming non-spherical cloud collapse, we find that relatively strong winds can carve out wide, conical outflow cavities and that relatively weak winds can be strongly collimated into jet-like structures. If the winds become weak enough, they can be cut off entirely by the infalling environment. We identify discrepancies between results from standard snowplow models and those presented here that have important implications for molecular outflows. We also present mass vs. velocity curves for comparison with observations.Comment: 35 pages, 11 figures (PNG and EPS