A variable gain PI to improve the performances of a unified power flow controller system

The instability problems in the electrical supply networks have had a great impact on recent research studies on modern devices. The unified power flow controller (UPFC) is one of the various FACTS (Flexible Alternative Current Transmission Sys-tems) devices that allow the electrical supply networks to be stable with a strong effectiveness. In this paper, the performances of such a device using both a classical PI and a variable gains PI controllers are examined. For this instance, the compensator is first stabilized before trying to stabilize the network. A series of comparative simulation tests have been undertaken for both regulators and analyzed. From the obtained results it is clearly shown that when the system is equipped with the variable gain PI regulator, the performance are much better

Comparative system dynamic modeling of a conventional and hybrid electric powertrain

© 2017 Taylor & Francis Group, London. Hybrid Electric Vehicles (HEVs) provide many known benefits over conventional vehicles, including reduced emissions, increased fuel economy, and performance. The high cost of HEVs has somewhat limited their widespread adoption, especially in developing countries. Conversely, it is these countries that would benefit most from the environmental benefits of HEV technology. As part of our ongoing project to develop a cost-effective and viable mild HEV for these markets, dynamic simulations are required to ensure that the proposed designs are to achieve their desired targets. In this paper, mathematical models of the powertrain are used to analyze and compare the dynamics of both a conventional power train and one with the addition of components required for the Mild Hybrid system. Using Matlab and Simulink, simulations of both powertrains under particular driving conditions are performed to observe the advantages of the MHEV over conventional drivetrains. These benefits include torque-hole filling between gear changes, increased fuel efficiency and performance

Transformations to groundwater sustainability: from individuals and pumps to communities and aquifers

If the success of agricultural intensification continues to rely on the depletion of aquifers and exploitation of (female) labour, transformations to groundwater sustainability will be impossible to achieve. Hence, the development of new groundwater imaginaries, based on alternative ways of organizing society-water relations is highly important. This paper argues that a comparative documentation of grass-roots initiatives to care for, share or recharge aquifers in places with acute resource pressures provides an important source of inspiration. Using a grounded anti-colonial and feminist approach, we combine an ethnographic documentation of groundwater practices with hydrogeological and engineering insights to enunciate, normatively assess and jointly learn from the knowledges, technologies and institutions that characterize such initiatives. Doing this usefully shifts the focus of planned efforts to regulate and govern groundwater away from government efforts to control individual pumping behaviours, to the identification of possibilities to anchor transformations to sustainability in collective action

Control Strategy for Three Phase Voltage Source PWM Rectifier Based on the Space Vector Modulation

This paper proposes the space vector pulse width modulation (SVPWM) control scheme for three-phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC-link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stable state performance and robustness against the load�s disturbance of PWM rectifiers are both improved. The simulation result shows feasibility of this strategy

L'expérimentation agronomique à l'heure du matériel lowcost : cas de la plaine agricole de Chenoua (Tipaza)

International audienceDes essais expérimentaux sur des cultures de concombre sous abri ont été conduits dans la plaine agricole de Chenoua (Tipaza) pour déterminer les conditions de fonctionnement des réseaux de goutte à goutte existants utilisant des eaux d'épuration et des eaux de nappe. Nous montrons que grâce à du matériel de mesure "lowcost", il est possible de produire de l'information utile qui permet d'établir un bilan d'eau et d'azote (modélisation agronomique) d'une part, et de dégager des relations débit-pression susceptibles de comprendre le fonctionnement des réseaux de goutte à goutte d'autre part. Des gaines de goutte à goutte également low cost ont été installées pour une durée d'une à deux années. Des mesures de débits par la méthode volumétrique (éprouvette) et de la pression à l'aide de manomètres à basse pression (< 1 bar) ont été effectuées au niveau des goutteurs dans deux serres de concombre. Les mesures de débit ont concerné 16 goutteurs bien répartis soient quatre rampes, sur chacune quatre goutteurs ont été sélectionnés : 2 aux extrémités et 2 au milieu. Quand à la pression elle a été prise en 3points : à l'entrée, au milieu de la serre et à la sortie pour diagnostiquer un éventuel effet de la position des goutteurs sur le colmatage. Un suivi horaire de la température et de l'humidité à l'intérieur de la serre a été réalisé par l'utilisation des thermohygromètres et ce afin d'établir un bilan hydrique dans la serre