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.

A Numerical Procedure for the Calculation of the Temperature Rise and Ampacity of Underground Cables

Abstract: A numerical procedure employing the finite element technique is developed for the calculation of the heat dissipation from a distribution duct bank. The procedure is used for calculating the conductor temperature and the ampacity of cables with and without forced cooling. The accuracy of the procedure is demonstrated by the comparison of the results with experimental findings. The accuracy, versatility and ease-of-use of the numerical procedure over presently employed analytical procedures show clearly the advantages of the numerical procedure.

The Dielectric Properties of Silicone Fluids

Abstract: The dielectric properties of polydimethylsiloxane fluids have been investigated under dc and ac fields as a function of field, frequency, temperature, and water content. The results of the ac studies have shown that the dielectric constant and dielectric loss of the fluid exhibit several transitions as a function of temperature at low temperatures. These transitions correlate reasonably well with structural changes in the fluid. The dielectric loss is also thermally activated and decreases rapidly with increasing frequency at ambient temperature. It is also weakly dependent on the applied field and the relative humidity. The dc properties exhibit a strong dependence of the conductivity on relative humidity. However, the dependence of the conductivity on the applied field is a complex one, and changes from an ohmic behavior at low fields, to a region of saturation at intermediate fields, and finally to an "ionization" region at high fields. The polydimethylsiloxane fluid also exhibits a reversal in the direction of the discharge current above a certain field, which is reminiscent of the electret effect observed in some polymeric solids. A tentative theoretical discussion of these properties is presented.

Quasi-Steady-State Approach for Analysis of Frequency Oscillations and Damping Controller Design

Abstract: This paper proposes a quasi-steady-state modeling approach for an approximation of long-term frequency dynamics in power systems. A specific phenomenon of concern is an onset of frequency swings during load/generation imbalance scenarios. The effects of system voltage characteristics, system inertia, and, more importantly, damping controllers are explained and quantified using the described quasi-steady-state models. Application of the methodology to a 14-generator benchmark system demonstrates that described models are suitable for simulation of different disturbance scenarios that can trigger frequency instability. Moreover, linearization of the proposed models can provide convenient means for impact assessment and coordinated design of damping controllers. To demonstrate this, coordinated tuning of multiband power system stabilizers to improve frequency dynamics has been performed and validated through nonlinear simulations using a commercial transient stability software.

Insertion properties of LiFe0.5Mn0.5PO4 electrode materials for Li-ion batteries

Abstract: This paper addresses the synthesis structural and electrochemical properties of LiFe0.5Mn0.5PO4 electrode materials for Li-ion batteries. The charge–discharge reaction of Li/LiPF6-EC–DEC/LiFe0.5Mn0.5PO4 cell carried out at the 1-C rate shows a capacity retention of 128 mAh/g. The local structure of the delithiated LixFe0.5Mn0.5PO4 phases have been studied by Fourier transform infrared spectroscopy and magnetometry. Spectral features indicate that the structure of the delithiated phase remains in the orthorhombic system. The compositional dependence of the magnetic moment is found to be in quantitative agreement with the theoretical value predicted for oxidation of M2+ ions in the high spin state.

Analysis of Power Flow in UPQC during Voltage Sag and Swell Conditions for Selection of Device Ratings

Abstract: This paper deals with the steady state analysis of unified power quality conditioner (UPQC). The UPQC, a combination of shunt and series active power filter (APF), is one of the best solutions towards the mitigation of voltage sags and swells problems on distribution network. The mathematical analysis is based on active and reactive power flow through the shunt and series APF, wherein series APF can absorb or deliver the active power whereas the reactive power requirement is totally handle by shunt APF alone during all conditions. The derived relationship between source current and % of sag/swell variation shows shunt APF plays an important role in maintaining the overall power balance in the entire network. The digital simulation is carried out to verify the analysis done. The simulation results support the mathematical analysis. The effect of load VAR variation and the impact of % sag / swell on the kVA ratings of both shunt and series APF are also analyzed. This analysis can be very useful for selection of device ratings for both shunt and series APFs.