Periodica Polytechnica (Budapest University of Technology and Economics)
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Adaptive Hierarchical Fractional-Order Sliding Mode Control Strategy for Multi-terminal VSC-HVDC System with Wind Farm
Get PDFIn this paper, an adaptive hierarchical fractional-order sliding mode controller (AHFSMC) for a multi-terminal Voltage Source Converter (VSC) based High Voltage Direct Current (HVDC) Integrated with a wind farm (WF) system is designed. Multi-terminal VSC-HVDC (MtVDC) connected to wind farms has received several attentions in the power sector because of its numerous benefits. The effectiveness of MtVDC, on the other hand, is dependent on the control scheme used. To achieve this goal, a hierarchical sliding mode control method by fractional-order calculus is used. The controller parameters are adjusted according to a suitable adaptation method to enhance the proposed controller's robustness compared to the system uncertainties coefficient. An appropriate Lyapunov-based approach is used to achieve the adaptation rule. This paper discusses a scheme to design additional controllers in MtVDC systems to damp electromechanical oscillations, one of several features of HVDC presently under active study. Numerical simulations validate the proposed control strategy's feasibility and efficiency. This novel approach is employed for the upgrading of system stability with the dynamic properties of the MtVDC in a variety of operative conditions
Mechanical Characterization of Hybrid Bagasse/Eggshell/E-glass Fiber-based Polyester Composite
Get PDFCurrently, numerous researchers, scientists, and industrialists are drawn towards utilizing natural fillers rather than synthetic ones because of their environmentally-friendly characteristics, lower density per unit volume and favorable mechanical attributes. Several studies have demonstrated that using organic filler in polyester matrix composites, instead of disposing of them in landfills, has various advantages. The current study focuses on the investigation of the mechanical characteristics of composite material made from a combination of bagasse, eggshell, and e-glass fibers exhibit characteristics such as strength under tension, strength under bending, resistance to indentation, and mass per unit volume. Different weight percentages of eggshell/bagasse were used to make the material using the hand lay-up technique (3wt%, 6wt%, 9wt%, and 12wt%), with 19wt% of glass fiber mixed in the resin. The use of inorganic fillers like calcium carbonate, a non-renewable mineral that may be expensive and environmentally hazardous to extract and process, is being reduced in favor of organic fillers like eggshell and bagasse, which are inexpensive and readily available. Specimens were generated by interposing fiber waste amidst chopped strand glass fiber mats, with variations in the bagasse, eggshell and polyester content, while keeping the amount of E-glass fiber constant. Afterward, the specimens were trimmed to the appropriate dimensions and subjected to analysis with a universal apparatus. The research showed that enhancing the quantity of bagasse/eggshell fiber within the hybrid composite resulted in an enhancement of its mechanical characteristics. The best reinforcement effect was observed in a hybrid composite with 6% bagasse/eggshell fiber
Vörös és barna: adalékok az európai diktatúrák könyvtárainak történetéhez (Szovjetunió, Német Birodalom, Magyar Népköztársaság) – recenzió
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Sonnevend, Péter (2024) Vörös és barna: adalékok az európai diktatúrák könyvtárainak történetéhez (Szovjetunió, Német Birodalom, Magyar Népköztársaság), Kovács, Katalin, Rácz, Ágnes (szerk.), Budapest, Gondolat Kiadó, ISBN: 978 963 556 529 0Könyvismertető
Sonnevend, Péter (2024) Vörös és barna: adalékok az európai diktatúrák könyvtárainak történetéhez (Szovjetunió, Német Birodalom, Magyar Népköztársaság), Kovács, Katalin, Rácz, Ágnes (szerk.), Budapest, Gondolat Kiadó, ISBN: 978 963 556 529
