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 New Predictors Based on the Concept of Center of Power for Transient and Dynamic Instability Detection

Abstract: This paper proposes a novel approach based on the center of power (COP) applied on a sliding window for real-time instability prediction. Synchrophasor measurements are obtained from phasor measurements units connected at strategic locations of the network. In order to assess the instability, the new concept of COP from which two new indices are derived is defined. These new indices are used as predictors in a detection algorithm based on random forest of decision trees. Three study cases carried out on the IEEE 4 generators 10 buses, the Australian 14 generators, and the New England test system allowed validating successfully the performance of the proposed method.

A two-level implicit scheme for the numerical solution of the linearized vorticity equation

Abstract: A numerical scheme is developed to study the stability of the linearized vorticity equations. The linear growth rates of Kelvin-Helmholtz instabilities resulting from a velocity shear are calculated numerically. The theory of neutrally stable waves, in two dimensions, is extended to include the cases where the stream function is zero or periodic at the boundary, and is verified numerically for the case of a velocity profile having the shape of a cosine function. The instability growth rates of the oscillations in the neighbourhood of the neutrally stable waves are calculated numerically and are shown to be in very good agreement with the theory. The results are also of interest in relation to studies on the instabilities of a two-dimensional guiding-centre plasma, and also in the study of the diocotron instability in electronics.

Thermal aging study of insulating papers used in power transformers

Abstract: Paper is a low-cost base material with outstanding mechanical and electrical properties, which is why it is still a key element in the insulation of electrical apparatus. Under the effect of a variety of factors including temperature, paper can substantially lose its properties, thus jeopardizing the service life of costly equipment. To remedy this situation, new so-called thermally upgraded papers are being made by certain manufacturers. A study carried out jointly by Hydro-Quebec, Electricite de France and the Ecole Nationale Superieure de Chimie de Toulouse has allowed researchers to qualify the thermal resistance of three different types of thermostable paper. These papers have been selected as being representative of what is available on the market today. The paper samples were subjected to two types of thermal aging tests in the presence of mineral oil in order to represent normal condition of operation (150/spl deg/C) as well as thermal failure (hot spot, 200/spl deg/C and 250/spl deg/C). The thermal degradation of the paper insulation is characterized by various physicochemical methods including measurement of the degree of polymerization, determination of 2-furfural in mineral oil by HPLC as well as determination of various sugars (monosaccharides, polysaccharides and anhydrosugars) in the paper using ion chromatography. This last method allows us to verify the formation of cellobiose, which is the real repeat unit of cellulose, as well as that of levoglucosan, which is an anhydrosugar and a precursor of 2-furfural. The evolution of all of these parameters, measured as a function of time, has allowed us to compare the thermal resistance of various insulating papers. The results of this study seem to show that, compared to traditional kraft paper, certain paper types are more susceptible to being thermally upgraded than others. This study also allowed us to demonstrate that the use of an inhibitor in mineral oil (DBPC) does not seem to influence the thermal degradation of these papers.