The control of voltage and reactive power is a major issue in power systems control and operation. Because of the topological differences between distribution and transmission systems, different strategies have evolved. Flexible AC Transmission Systems (FACTS) controllers, such as the Thyristor Controlled Voltage Regulator (TCVR), employ the latest technology of power electronic switching devices in electric power transmission systems to control voltage and improve voltage regulation. This paper presents an impact study of using TCVR on the fault current calculations in case of a ground fault. The case study is a high voltage transmission line in the Algerian power network. The analysis is based on symmetrical components method which includes symmetrical components of current and voltage as well as the transmission line currents and line voltages, without and with TCVR in the presence of fault resistance. In this research work, the obtained simulation results match the presented theoretical analysis.
Although the risk graph method, described by the IEC 61508 standard is widely used for the determination of Safety Integrity Levels for the Safety Instrumented Functions (SIF) which performed by Safety Instrumented Systems (SIS). This technique has limits regarding the linguistic interpretation of the parameters of the risk analyzed. In addition, the calibration of the risk graph method as defined at the IEC61511 standard consists to use discrete intervals include also a problem of uncertainty in the calculation of Safety Integrity Levels. The purpose of this work is to improve of conventional risk graph in order to ensure a better implementation of safety instrumented systems (SIS). The proposed model based on fuzzy rules, considers the parameters defining the risk graph as inputs of a fuzzy inference systems and the Safety Integrity Level (SIL) as unique output. In order to validate the proposed model, a case study on an industrial system is carried out. The obtained results show a particular interest of fuzzy graph risk for estimating the appropriate Safety Integrity Level than that given by the risk graph conventional.
Located in the Aures mountains Foum Toub is characterized by an annual average rainfall of 800mm. The hydrology subordinate to the terrain is the direct consequence of surface waters and of snow melting from the heights of Chelia Mountain. The aim of the implantation of the Foum Toub backwater is to minimize the siltation phenomenon at the upstream of the Koudiate El Mdaour dam, to regularize the Rebaa creek flow which runs from south to north and to contribute to the irrigation of the Foum Toub plain. This study puts the emphasis on the mobilization of surface water resources, a policy of the Ministry of Agriculture and Rural Development with a view to rationalize the use and planning of this vital factor, i.e. water. The site selected for the construction of this structure is characterized by a waterproof marly substratum, favourable for implanting the dike and the basin. The clay-silty-gravelly material furniture localized in the depressions as well as sandstones are used as areas for the construction materials of this structure. Stability is one of the most important parameters to take into account for the choice of the site, so as to avoid any problem linked to the withdrawal-swelling phenomena on the banks of creek. However, the sliding possibility, however weak it is, can be generated on the left bank of the creek within deposit and recent silt. The choice of the site for the implantation of this hydraulic structure remains subject to laboratory tests.
This paper presents a comparison between the two diagnosis approaches of linear closed-loop systems; sequential approach and integrated approach. An application of these two approaches for a DC motor will be introduced at the end to have the advantage and inconvenient one and the other for electrical entertainment.
The community of nematodes (Nematoda: Secernentea) in groves of North East Algeria, has been the subject of regular observations of September 2011 to May 2012. Sampling and extraction of nematodes by the buckets technique are conducted following the method of Baermann. The sampling groves are composed by olive trees (Olea europea: Oleaceae) from four varieties: Chemlal, Sigoise, Frontoï and Sévillane. We identified a total of 531 individuals. The systematic inventory revealed 14 genus of Nematoda, belonging to 10 families and 3 orders. The Tylenchida and Dorylaimida are the best represented orders. They represent 92.85% of the total community of all identified nematodes, while Aphelenchida represent only 7.15%. The genus Pratylenchus records alone 54.75% on the Sévillane variety and 33.02% on the Frantoi variety. The most represented genus on Sigoise and Chemlal varieties is Meloidogyne with respectively 43.24% and 30.43%. Grove of Sévillane variety hosts the highest abundance of nematodes with 57.44%; against only 19.96%, 13.94% and 8.66%, respectively, for the varieties Frantoi, Sigoise and Chemlal. Depending on the seasons, nematodes are more abundant in autumn (88.52%) than in winter (8.66%) and the spring (2.82%). Pratylenchus and Meloidogyne are noted with large numbers, especially in winter.
