Hydro-Québec

About: Hydro-Québec is a government organization based out in Montreal, Quebec, Canada. It is known for research contribution in the topics: Electric power system & Dielectric. The organization has 2596 authors who have published 4433 publications receiving 100878 citations.

Development of inductive fault current limiters up to 100 kVA class using bulk HTS materials

Abstract: Since 1992, Hydro-Quebec has been developing prototypes of screened iron core fault current limiters for medium voltage distribution networks. Fault current limiters (FCLs) are amongst the most promising applications of high temperature superconductors. The unique properties of HTS such as high T/sub c/ and high resistivity in the flux flow state make them suitable for a design based on bulk materials. A 100 kVA class inductive study prototype of SFCL built around five commercial Bi-2212 hollow tubes (Hoechst) has been repeatedly tested at /spl sim/600 V RMS in nominal and fault conditions. In particular, the thermal stability has been investigated as a function of the temperature of the nitrogen bath (67-77 K). Simulation of the behaviour of the inductive limiter using differential equations are presented where both electromagnetic and thermal behaviour are considered. Part of this work is done within the joint collaboration between Hydro-Quebec and Siemens.

Toward Low-Cost All-Organic and Biodegradable Li-Ion Batteries.

Abstract: This work presents an alternative method for fabricating Li-ion electrodes in which the use of aluminum/copper current collectors and expensive binders is avoided. Low-cost natural cellulose fibers with a 2-mm length are employed as binder and support for the electrode. The objective of this method is to eliminate the use of heavy and inactive current collector foils as substrates and to replace conventional costly binders with cellulose fibers. Moreover, no harmful solvents, such as N-methylpyrrolidone, are employed for film fabrication. Water-soluble carbons are also utilized to reduce the preparation time and to achieve a better repartition of carbon in the electrode, thus improving the electrochemical performance. Flexible and resistant LiFePO4 (LFP), Li4Ti5O12 (LTO), organic 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), and graphite electrodes are obtained with active mass loadings similar to those obtained by the current casting method. The initial discharge capacity of approximately 130 mAh·g−1 at 2 C is obtained for an LFP/LTO paper battery with an approximately 91.6% capacity retention after 1000 cycles. An all-organic prelithiated PTCDA/graphite cell without a transition metal is prepared and electrochemically tested. It is one of the first self-standing batteries that is composed of organic redox active molecules and biodegradable components reported in literature.

Dielectric barrier discharges in atmospheric pressure helium in cylinder-plane geometry: experiments and model

Abstract: The discharge behaviour of metallic cylinder-dielectric plane gaps in flowing helium was examined under atmospheric pressure at a frequency of 10 kHz as a function of gap length and applied voltage. The high-voltage electrode consisted of a steel cylinder with a radius of 3.15 mm, with alumina (Al2O3) or glass plates being utilized as low-potential electrodes. The bottom surface of the low-potential electrodes was covered with a thin Al layer (alumina plate) or an ITO layer (glass plate) that formed the grounded counter-electrodes. The electrical and photoemission currents were recorded simultaneously and precisely synchronized with an ultra-high-speed intensified charge coupled device camera for recording the discharge patterns. The experimental results were compared with those derived from a mathematical model on the basis of the continuity equations for electrons, ions and excited particles and the Poisson equation. The influence of surface charge on the dielectric electrodes on the time evolution of the helium discharge was analysed, and the experimental and theoretical vertical (y(t)) and horizontal (x(t)) dimensions of the discharges were determined for different low-potential electrode arrangements. A reasonable agreement was obtained between the measured and calculated y(t) and x(t) values.

The compensation law revisited-Application to dielectric aging

Abstract: The fundamental origin of the compensation law observed by P. K. David (1987, 1988) and G. C. Montanari (1988) in several aging mechanisms of dielectrics is discussed. It is shown that this is due to a linear relation between activation entropy and enthalpy of a given process. An aging model, partially based on the rate theory, is presented. One of its advantages is that it characterizes dielectric aging by a free energy change, rather than by an apparent activation energy. Some aging data are analyzed with the proposed model, and it is shown that under high stresses the failure time varies exponentially with stress. Some critical comments are made regarding the use of arbitrary end points as a method of selection for a failure criterion. >

Comparison of two modeling approaches for groundwater-surface water interactions.

Abstract: An assessment of interactions between groundwater and surface water was carried out by applying two different modeling approaches to a small-scale study area in the municipality of Havelock, Quebec. The first approach involved a commonly used sequential procedure that consists in determining the daily recharge rate using a quasi 2D infiltration model (HELP), applied in the next step as an imposed flux to a 3D finite-element groundwater flow model. The flow model was calibrated under steady-state and transient conditions against measured water levels. The second approach was based on a recently developed physically based, 3D fully coupled groundwater–surface water flow model (CATHY) applied to the entire flow domain in an integrated manner. Implementation, calibration, and results of the simulations for both approaches are presented and discussed. For equal annual precipitation (1038 mm/y) and evapotranspiration (556 mm/y), the second approach computed a recharge rate of 233 mm/y (8.9% higher than the first approach) and a net upward flow from the fractured aquifer (the first approach predicted a net downward flow to the rock). The simulated annual discharge was similar for the two approaches (9.6% difference). Both approaches were found to be useful in understanding the interactions between groundwater and surface water, although limitations are apparent in the sequential procedure's inability to account for surface–subsurface feedbacks, for instance near stream reaches where groundwater discharge is prevalent. The decoupled, two-model approach provides disaggregated surface, vadose, and aquifer flows, and a simple apercu at the different components of total discharge. The fully coupled model accounts for continuous water exchanges between the land surface, subsurface, and stream channel in a more complex manner, and produces a better match against observed data. Copyright © 2012 John Wiley & Sons, Ltd.