نتایج جستجو برای: grid system
تعداد نتایج: 2285670 فیلتر نتایج به سال:
Abstract Traditional railway power supply systems impose substantial power quality problems (PQ) on the utility network, such as unbalance, harmonics and a large amount of reactive power. This paper proposes a topology based on three-phase to single-phase modular multilevel converters (MMC) to obviate these problems. The MMC based traction substations (TSS) are connected directly to the utili...
Because of installation for local consumers and since it is free of all contaminations, connecting photovoltaic cells to the grid via single-phase inverter is significantly on the rise. In this paper, a new simple current control is proposed for a single-phase grid-connected voltage source inverter. Using the PQ theory and modelling a single-phase system as an unbalanced three-phase system, a m...
The article presents the transients analysis of the substation grounding systems and transmission line tower footing resistances which can affect to the back-flashover (BF) or overvoltage across insulator chain in an HV power systems by using EMTP-RV software. The related transient modeling of the grounding systems is based on a transmission line (TL) model with considering the soil ionization....
design of bridge deck with long-term strength, durability and permanence is a significant interest for engineers. one applicable solution to this challenge could be via using hybrid system consisting of conventional materials such as concrete and steel with frp plates which is also known as composite deck. since these deck are relatively new so their performance is not completely known. the pre...
The thin-layer Navier-Stokes equations are solved for two complete missile configurations on an IBM 3090-200 vectro-facility supercomputer. The conservation form of the three-dimensional equations, written in generalized coordinates, are finite differenced and solved on a body-fitted curvilinear grid system developed in conjunction with the flowfield solver. The numerical procedure is based on ...
In recent years, most of the loads and distributed generations are connected to the AC grid through the power electronic converters. Using the DC grid beside the AC grid can reduce the conversion stages and power losses. Protection of the DC grids is a challenging issue because of the new structures of DC grids and fast transients of the DC faults. This paper studies the protection of the low v...
in this study, flow characteristics through symmetric stenosis artery are investigated. the shape of eccentricity for stenotic flows is limited by circular-cross sections and plaques are usually assumed as to be oriented concentrically. thegoverningequationsaretheusualnavier-stokesequationsandare numericallysolved by using finite volumemethod in arbitrary orthogonal curvilinear coordinates. in ad...
orography plays a substantial role in the formation and evolution of many atmospheric phenomena. observations indicate that two mountain ranges to the southwest of the red sea and west of iran (zagross mountain range) play a crucial role in the formation, evolution and activities of synoptic weather systems over iran. observations also, indicate that there are considerable differences between t...
As an efficient alternative to fossil fuels, renewable energy sources have attained great attention due to their sustainable, cost-effective, and environmentally friendly characteristic. However, as a deficiency, renewable energy sources have low reliability because of their non-deterministic and stochastic generation pattern. The use of hybrid renewable generation systems along with the storag...
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