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.

Low stray interconnection inductance power converting molecule for converting a DC voltage into an AC voltage, and a method therefor

Abstract: The low stray interconnecton power converting module is for converting a DC voltage into an AC voltage. It comprises two DC voltage terminals for receiving the DC voltage, an AC voltage terminal for delivering the AC voltage, and a half-bridge including a pair of power switching elements connected as a series totem pole between the DC voltage terminals via the AC voltage terminal. It also comprises a decoupling device for decoupling the half-bridge. The decoupling device comprises a series of at least two adjacent superimposed electrode plates separated by a dielectric material and extending proximately in overlapping relation with the half-bridge. Each of the adjacent electrode plates is connected to a different one of the DC terminals. The electrode plates form with the two power switching elements, the DC terminals and the AC terminal, a reduced cross section belt-like current closed loop by which a low stray interconnection inductance power converting module is obtained.

Small signal analysis of hydro-turbine governors in large interconnected power plants

Abstract: The paper describes a transient stability program (TSP) based approach to identify numerically, a state-space, small-signal model of the open-loop system seen by the hydro-turbine governor during its normal operation. This single-input multiple-output model is validated successfully by comparing actual closed-loop responses computed in the TSP with those simulated in Matlab using the linearized model. For illustration, three governing systems found in the Hydro-Quebec's grid are studied: (1) a mechanical hydraulic; (2) a Woodward PID; and (3) a classical Neyrpic's governor. System performance with respect to the speed of response, interarea modes sensitivity and closed-loop gain and phase margins is assessed, evidencing the somewhat detrimental impact of the derivative control term for interconnected operation. Overall, the small-signal analysis approach devised appears well-suited for determining and/or assessing unit-connected settings of hydro-turbine speed governing systems.

Nanostructured epoxy/POSS composites: enhanced materials for high voltage insulation applications

Abstract: In this study, the dielectric and thermal properties of nanostructured epoxy/POSS (Polyhedral Oligomeric Silsesquioxanes) composites were investigated, using a reactive Triglycidylisobutyl-POSS (TGIB-POSS) additive from 1 up to 10 wt%. POSS has been successfully dispersed at a molecular level for low content composites, which show a remarkably improved resistance to corona discharges, with up to 60% less eroded sample volume, along with significantly increased dielectric breakdown strengths and thermal conductivities. Epoxy/POSS composites containing 5 wt% and more of the POSS additive exhibit agglomerations, which have been observed by SEM. Furthermore, dielectric spectroscopy revealed additional interfacial loss peaks for such composites containing 5 wt% POSS and more, in addition to the α- and β-peaks known for epoxy.

Nanoscale Lithium Quantification in Li X Ni y Co w Mn Z O 2 as Cathode for Rechargeable Batteries

Abstract: Time-of-flight secondary ion mass spectrometry (TOF-SIMS) using a focused ion-beam scanning electron microscope (FIB-SEM) is a promising and economical technique for lithium detection and quantification in battery materials because it overcomes the limitations with detecting low Li content by energy dispersive spectroscopy (EDS). In this work, an experimental calibration curve was produced, which to our best knowledge allowed for the first time, the quantification of lithium in standard nickel manganese cobalt oxide (NMC-532) cathodes using 20 nm resolution. The technique overcomes matrix effects and edges effects that makes quantification complex. This work shows the high potential of TOF-SIMS tool for analytical characterization of battery materials, and demonstrates its tremendous capabilities towards identification of various chemical or electrochemical phenomena in the cathodes via high-resolution ion distributions. Various phenomena in the ion distributions are also assessed, such as edge effects or measurement artifacts from real signal variations.

High-Capacity and Long-Cycle Life Aqueous Rechargeable Lithium-Ion Battery with the FePO4 Anode.

Abstract: Aqueous lithium-ion batteries are emerging as strong candidates for a great variety of energy storage applications because of their low cost, high-rate capability, and high safety. Exciting progress has been made in the search for anode materials with high capacity, low toxicity, and high conductivity; yet, most of the anode materials, because of their low equilibrium voltages, facilitate hydrogen evolution. Here, we show the application of olivine FePO4 and amorphous FePO4·2H2O as anode materials for aqueous lithium-ion batteries. Their capacities reached 163 and 82 mA h/g at a current rate of 0.2 C, respectively. The full cell with an amorphous FePO4·2H2O anode maintained 92% capacity after 500 cycles at a current rate of 0.2 C. The acidic aqueous electrolyte in the full cells prevented cathodic oxygen evolution, while the higher equilibrium voltage of FePO4 avoided hydrogen evolution as well, making them highly stable. A combination of in situ X-ray diffraction analyses and computational studies reveal...