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Electrical System (electrical + system)

Distribution by Scientific Domains

Engineering	66%

Selected Abstracts

Short-term scheduling of a wind generation and hydrogen storage in the electricity market

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2010
G. Tina
Abstract Intermittent renewable energy sources (RES) are promising to be the future of electricity generation. In particular wind generation, owing to its stochastic behaviour, has to be carefully managed. Its lack of sufficient predictability decreases the energy value in the current framework of electrical markets, therefore, beyond a certain threshold; this kind of generation into the electrical system represents a problem for the transmission system operator (TSO) during its despatching service. The coupling of wind energy conversion system (WECS) with a storage medium (i.e. hydrogen) could improve the programmability of such generation plants in electrical markets. In this paper, an economical optimization tool has been developed in order to find the short-term scheduling so as to maximize the economic revenues in the day-ahead electricity market of a storage plant coupled with a wind farm. This tool needs as input the forecasts of both wind generation power and market prices, obtained with the adoption of pre-processing input data algorithm based on different methods that involve both statistical and probabilistic approaches. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Muscle preservation using an implantable electrical system after nerve injury and repair

MICROSURGERY, Issue 6 2001
F.R.C.S.(C), Stephen C. Nicolaidis M.D.
The value of continuous electrical stimulation of denervated muscles after nerve injury and repair has been clearly shown in a series of laboratory experiments in three animal models. This experimental background, which showed improved muscle preservation and better functional results, evolved into a clinical study that included 15 patients with peripheral nerve injuries in the upper extremities, 3 patients with brachial plexus injuries, and three patients with facial nerve paralysis. Improved functional results were obtained using this implantable system, which were similar to those achieved with the animal experiments. All patients had muscle stimulation for extended periods ranging from 127 to 346 days. Analysis of the results showed satisfactory nerve regeneration on clinical examination and with electromyographic studies. Functional muscle analysis varied somewhat from patient to patient, but every patient had a satisfactory to excellent recovery. The results from this study have clearly shown the benefits of continuous muscle stimulation using an implantable electrical system after nerve injury and repair expansion of the project to a larger patient cohort is indicated. © 2001 Wiley-Liss, Inc. MICROSURGERY 21:241,247 2001 [source]

Effects of moisture content, impulse polarity and earth electrode's dimension on dry and wet sand under high voltage conditions

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 5 2008
N. Mohamad Nor
Abstract The study on the physics of discharges in soil and performance of earthing networks subjected to lightning currents are important in order to improve the reliability of electrical systems and to obtain better electrical models of earthing systems. The soil characteristics of various moisture contents under high-impulse currents have been well studied in previous studies. In this present study, fast impulse generator is used to investigate the dry soil characteristics in two cylindrical test cells of different outer radii; 15 and 20,cm under high magnitude fast impulse conditions of both impulse polarities. This allows to study the characteristics of dry soil under high-impulse current conditions, and allows a comparison between the dry and wet soil characteristics under high-impulse conditions such as before and after breakdown of the test cell. In this study, the effects of impulse polarities, moisture content in soil and the outer dimensions of test cell on the soil characteristics under high-impulse currents were investigated. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Practical aspect of active and generating powers in nonsinusoidal situations: Some questions

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 6 2001
Alexander E. Emanuel
Many modern apparent power resolutions are based on the Fryze's active power as well as on the generating power. This paper scrutinizes the usefulness of Fryze's active power subcomponents and the very existence of the generating power in real life electrical systems. [source]

Models of non-smooth switches in electrical systems

INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 3 2005
Christoph Glocker
Abstract Idealized modelling of diodes, relays and switches in the framework of linear complementarity is introduced. Within the charge approach, the classical electromechanical analogy is extended to passively and actively switching components in electrical circuits. The associated branch relations are expressed in terms of set-valued functions, which allow to formulate the circuit's dynamic behaviour as a differential inclusion. This approach is demonstrated by the example of the DC,DC buck converter. A difference scheme, known in mechanics as time stepping, is applied for numerical approximation of the evolution problem. The discretized inclusions are formulated as a linear complementarity problem in standard form, which implicitly takes care of all switching events by its solution. State reduction, which requires manipulation of the set-valued branch relations in order to obtain a minimal model, is performed on the example of the buck converter. Copyright © 2005 John Wiley & Sons, Ltd. [source]