Current Issue : January - March Volume : 2021 Issue Number : 1 Articles : 5 Articles
This paper presents the energy saving method by applying the voltage control\ntechnique on a single-phase AC source to a thyristor rectifier and an IGBT\ninverter with LC filter. Based on the LC filter parameter, the values of the gain\nfor the controller are obtainable. The proposed controller structure consists\nof two loops arranged in a cascaded model. The output of the first loop is the\ncapacitor current. This current is added to the load current in order to obtain\nthe current reference. This reference current value will be compared with the\ninverter current which produces the error signal to be fed into the second\nloop in the cascade system....
The performance of solar PV modules is significantly affected by temperature.\nThis paper focuses on the determination of the effect of temperature on\na commercial mono-crystalline silicon PV module whose temperature coefficients\nwere not provided by the manufacturer for installation in Kumasi,\nGhana, Sub-Saharan Africa (SSA) ambient................................
In this paper, the maximum obtainable energy from a galloping cantilever beam is found. The system consists of a bluff body in\nfront of wind which was mounted on a cantilever beam and supported by piezoelectric sheets. Wind energy caused the transverse\nvibration of the beam and the mechanical energy of vibration is transferred to electrical charge by use of piezoelectric transducer.\nThe nonlinear motion of the Eulerâ??Bernoulli beam and conservation of electrical energy is modeled by lumped ordinary\ndifferential equations. The wind forces on the bluff body are modeled by quasisteady aeroelasticity approximation where the fluid\nand solid corresponding dynamics are disconnected in time scales. The linearized motion of beam is limited by its yield stress\nwhich causes to find a limit on energy harvesting of the system. The theory founded is used to check the validity of previous results\nof researchers for the effect of wind speed, tip cross-section geometry, and electrical load resistance on onset speed to galloping, tip\ndisplacement, and harvested power. Finally, maximum obtainable average power in a standard RC circuit as a function of\ndeflection limit and synchronized charge extraction is obtained....
A rapid decarbonisation of power systems is underway in order to limit greenhouse gas emissions and meet carbon-reduction\ntargets. Renewable energy is a key ingredient to meet these targets; however, it is important that national power systems still\nmaintain energy security with increasing levels of renewable penetration. The operating potential of renewable generation at times\nof peak demand (a critical time for power system stress) is not well understood. This study therefore uses a multidecadal dataset of\nnational demand, wind power, and solar power generation to identify the meteorological conditions when peak demand occurs\nand the contribution of renewables during these events. Wintertime European peak power demand events are associated with high\natmospheric pressure over Russia and Scandinavia and are accompanied by lower than average air temperatures and average wind\nspeeds across Europe. When considering power demand extremes net of renewable power production, the associated meteorological\nconditions are shown to change. There is considerable spatial variability in the dates of national peak demand events and\nthe amount of renewable generation present. Growth in renewable generation has the potential to reduce peak demands.\nHowever, these impacts are also not uniform with much larger reductions in peak demand seen in Spain than in central Europe.\nThe reanalysis-derived energy models have allowed recent peak demand events to be put into a long-term context....
Both the modeling and the load regulation capacity prediction of a supercritical\npower plant are investigated in this paper. Firstly, an indirect identification\nmethod based on subspace identification method is proposed. The obtained\nidentification model is verified by the actual operation data and the\ndynamic characteristics of the system are well reproduced. Secondly, the model\nis used to predict the load regulation capacity of thermal power unit. The\npower, main steam pressure, main steam temperature and other parameters\nare simulated respectively when the unit load is going up and down. Under\nthe actual constraints, the load regulation capacity of thermal power unit can\nbe predicted quickly....
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