Динамическая устойчивость работы ветроэлектростанций в составе электроэнергетических систем

Объектом исследования являются: модели энергосистем, тепловая электростанция мощностью 556 МВт. Цель работы – исследование динамической устойчивости крупных ветроферм, работающих в энергосистеме, оценка влияния внедрения ветроэлектростанций на динамическую устойчивость синхронных генераторов энергосистемы. Выпускная квалификационная работа выполнена с помощью программ MS Excel, MS Visio, PSS/E, EnergyPRO Software в текстовом редакторе MS Word.Objects of the research: power system models, thermal power station with total capacity 556 MW. Object of the work – investigation of dynamic stability of large wind farms, working in power system, evaluation of wind farms implementation influence on large synchronous generators of power system. Master thesis work was performed in MS Word, MS Excel, MS Visio, PSS/E, EnergyPRO Software

Absolute values of surface and step free energies from equilibrium crystal shapes

It is shown that exact images of the three-dimensional equilibrium shape of crystallites (ECS), recorded at several temperatures between 0.3 and 0.8 of the melting temperature of a solid, can be evaluated to yield absolute values of the surface and step free energies versus temperature, in addition to the formation energy of kinks. The essential input for this novel approach is the temperature variation of the size of a facet on the ECS and of the separation between the Wulff point and that particular facet. This approach promises access to surface free energies over a large temperature range and for well-defined low-index surface orientations

Absolute step and kink formation energies of Pb derived from step roughening of two-dimensional islands and facets

The shapes of (111) oriented two-dimensional (2D) islands and facets, the latter being part of three-dimensional (3D) crystallites of Pb, were equilibrated at 104-520 K. Island sizes were in the range of 15-90 nm radius, facets typically at 100-270 nm radius. They were imaged by scanning tunneling microscopy to provide the exact outline of the bounding step. Increased step roughening with increasing temperature decreases the radius anisotropy of islands and facets in a consistent manner. Products of island/facet radius times local step curvature versus temperature were obtained experimentally, serving as the basis of absolute step and kink energies at 0 K. They are f(1A)(0)=128.3+/-0.3 meV, f(1B)(0)=115.7+/-5.8 meV, and epsilon(kA)=42.5+/-1.0 meV, epsilon(kB)=60.6+/-1.6 meV, respectively. The combination of studying small 2D islands (unstable at high temperature) and large 2D facets allows measurements over a very large range of temperatures

Experimental absolute step and kink formation energies on Pb(111) vicinal surfaces

Three-dimensional crystallites of Pb, equilibrated at various temperatures and imaged by scanning tunneling microscopy at temperature, have provided the basis for a quantitative determination of absolute step free energies and kink formation energies of vicinal Pb(l 11) surfaces. The anisotropy of large (111) facets was evaluated as a function of temperature. Products of radius times local curvature for A and B-steps of these facets were calculated and their dependence on temperature fitted by theoretical expressions. Absolute values of step energies at 0 K are f(1A) (0) = 131 meV and f(1B)(0) = 117 meV, with the corresponding kink energies Of epsilon(kA) = 40.0 meV and epsilon(kB) = 60.3 meV. (C) 2001 Elsevier Science B.V. All rights reserved