Current Issue : January - March Volume : 2017 Issue Number : 1 Articles : 6 Articles
The mixed power flow analysis method decreases the computational complexity and\nachieves a high level of simulation accuracy. The mixed approach combines the ac with the dc\npower flow models, depending on the area of interest. The accurate ac model is used in the study\narea of interest to obtain high simulation accuracy, while the approximate dc model is used in the\nremainder of the system to reduce the required computations. In the original mixed approach,\nthe errors originating from the use of the dc model may propagate to the area of interest where\naccurate simulation outcomes are required; thus, the simulation accuracy might not be satisfactory.\nThis paper presents a new method of enhancing the simulation accuracy of the mixed power flow\nanalysis using available information. In the proposed approach, a modified dc model is used instead\nof the traditional one and is constructed from an initial base-case ac solution. The new dc model\ncompensates for the errors originating from the neglect of the real power losses and the assumption of\na flat voltage magnitude in the conventional dc model. Thus, the proposed method can improve the\nsimulation accuracy in the area of interest. The superior computational benefits can also be preserved\nby maintaining linear characteristics of the dc model. Case studies with the IEEE 118-bus system are\nprovided to validate the enhanced accuracy of the proposed method....
Small-scaled wind turbine is converted to mechanical power of windmill to electric\npower by generator. However almost all studies seems to have overlooked converting\nrelation of mechanical & electric power. It the reason for was very difficult establishing\nwind turbine system. In this paper, it is define equation of converting relation of\nmechanical & electric power. And it is verified by experimental methods. Defined\nequation will be used in developing electric devices such as inverter and controller in\nwind turbines. In addition this method can be used in the fields that utilize the rotational\npower into electrical power through generator....
The situation of electricity in Pakistan has been alarming from the last ten years. The\ndeficiency in electricity has not only obstructed the business activities but also affected\nthe domestic consumers, educational institutes and hospitals. Usually electrical power\ncompanies are liable for electricity shortfall and power interruption. However, electricity\nend consumers are also equally responsible behind strange shortfall and unusual\npower interruption. Frequently, the consumers use the heavy electrical equipment in\ntheir homes including heaters, geysers, irons and water motors which causes the more\nelectricity consumption, load shedding and huge amount of bills. For escaping the\nhuge amount of electricity bill, the consumers commit the illegal and unethical connections.\nThe illegal usage of electrical power failed the power companies to plan schedule\nload shedding accordingly and the other side the damaged electricity wires or Pole\nMount Transformer increased faults due to overburdening, which directly affected on\nextend power interruption. In addition that, responsible teams of electrical power\ncompanies cannot reach instantly to repair faults and prevent the theft. Electricity\nthieving is social crime committed by the consumers or meter readers which causes the\nelectricity strange shortfall within country. This paper presents the practical demonstration\nabout the common energy theft methods and techniques done by electricity\nconsumers within their home and residential building. In Pakistan EPC (electrical\npower companies) deploy the traditional electromechanical meters for electricity consumption\nmeasurements, however, these meters do not have any real time communication.\nTherefore there are many easy ways to manipulate the meter reading as well as\ninternal structural of metering system...
Bitter coils are electromagnets used for the generation of extremely strong magnetic fields superior to 30 T. In this paper we calculate\nthe mutual inductance and the magnetic force between Bitter disk (pancake) coil with the nonlinear radial current and the circular\nfilamentary coil with the azimuthal current. The close form expressed over complete elliptic integrals of the first and second kind as\nwell as Heuman�s Lambda function is obtained for this configuration either for themutual inductance or for the magnetic force.The\nresults of this method are compared with those obtained by the improved modified filament method for the presented configuration.\nAll results are in an excellent agreement....
An opportunity wireless charging system for electric vehicles when they stop and wait\nat traffic lights is proposed in this paper. In order to solve the serious power fluctuation caused by\nrandom access loads, this study presents a power stabilization strategy based on counting the number\nof electric vehicles in a designated area, including counting method, power source voltage adjustment\nstrategy and choice of counting points. Firstly, the circuit model of a wireless power system with\nmulti-loads is built and the equation of each load is obtained. Secondly, after the counting method of\nelectric vehicles is stated, the voltage adjustment strategy, based on the number of electric vehicles\nwhen the system is at a steady state, is set out. Then, the counting points are chosen according to\npower curves when the voltage adjustment strategy is adopted. Finally, an experimental prototype is\nimplemented to verify the power stabilization strategy. The experimental results show that, with the\napplication of this strategy, the charging power is stabilized with the fluctuation of no more than 5%\nwhen loads access randomly....
This paper presents the optimization technique for minimizing the voltage and current total\nharmonic distortion (THD) in a single-phase multilevel inverter controlled by staircase modulation.\nThe previously reported research generally considered the optimal THD problem in the frequency\ndomain, taking into account a limited harmonic number. The novelty of the suggested approach\nis that voltage and current minimal THD problems are being formulated in the time domain as\nconstrained optimization ones, making it possible to determine the optimal switching angles. In\nthis way, all switching harmonics can be considered. The target function expression becomes very\ncompact and existing efficient solvers for this kind of optimization problems can find a solution\nin negligible processor time. Current THD is understood as voltage frequency weighted THD that\nassumes pure inductive loadââ?¬â?this approximation is practically accurate for inductively dominant\nRL-loads. In this study, the optimal switching angles and respective minimal THD values were\nobtained for different inverter level counts and overall fundamental voltage magnitude (modulation\nindex) dynamic range. Developments are easily modified to cover multilevel inverter grid-connected\napplications. The results have been verified by experimental tests....
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