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 static compensator model for the EMTP

Abstract: A static voltampere-reactive (VAr) compensator (SVC) model based on nodal analysis, is presented. The model is integrated in the electromagnetic transients program (EMTP) with minimal interface error and by taking into account initialization. The model is basically a generic compensator using thyristor controlled reactors. The models are modular to represent adequately compensators of different designs while being detailed enough for predicting possible harmonic interactions between the AC system and the SVC. Typical applications on the Hydro-Quebec system are described. >

Stress predictions in a Francis turbine at no-load operating regime

Abstract: In the operation of hydraulic turbines, no-load and very low load conditions are among the most damaging. Even though there is no power generation, there is still a significant amount of energy which has to be entirely dissipated, mainly in the runner, where the flow is quite complex, with large scale unsteady and chaotic vortices resulting from partial pumping. This paper presents different approaches to perform stress analyses at low load conditions on a Francis turbine, taking into account the pressure fluctuations on the runner blades due to the large stochastic flow structures inherent in no-load operating regimes. With appropriate mesh density and time step, unsteady computational fluid dynamics (CFD) simulations using the SAS-SST turbulence model can be used on a Francis runner to predict the pressure fluctuations with reasonable accuracy when compared to measurements. These calculated pressure loads can then be used to predict the dynamic stresses with finite-element analyses (FEA). Different approaches are discussed ranging from quasi-static single-blade models to full runner time- dependent one-way fluid-structure interaction (FSI). Pros and cons of the different modelling strategies will be discussed in a detailed analysis of the structural results with comparisons to experimental data. Once the time signal of the stochastic stress at no-load conditions is obtained, the runner fatigue damage related to this operating condition can be estimated using different tools such as time signal extrapolation and rainflow counting.

Large-scale active-load modulation for angle stability improvement

Abstract: Analyses, operating experience and simulations of a large power system are used to demonstrate that active-load modulation can improve the system's dynamic performance to a large extent, with just a fraction of the base load available for control. At a time when the cost effectiveness of FACTS devices for damping interarea oscillations is constantly being questioned, it is natural to look to active-load modulation as a potential alternative method of insuring grid reliability. In developing the case, it was found that continuously modulating load stabilizers need to be fed with global signals for full efficiency. Although more difficult to design, implementation of a discontinuous control scheme shows good prospects, especially with regard to decentralization and robustness against communication delays.