Browsing by Author "Vargas, Luis"

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    Optimal Capacity Expansion in Electric Power Subtransmission Networks
    (ASCE-AMER SOC CIVIL ENGINEERS, 2009) Tapia, Felipe; Marianov, Vladimir; Vargas, Luis
    A procedure is proposed to determine where and when to increase the capacity of lines and transformers in a power subtransmission network. The expansion plan must minimize cost while supplying the demand for energy over a time horizon, keeping the quality and reliability standards of the network and minimizing the impact over the environment. The procedure is iterative and takes into account AC flows, reliability analysis, different scenarios, demand uncertainty, discrete investment costs, voltage constraints, capacity, and power factor. A significant contribution of this procedure is that, along with the expansion plan, it considers the optimization of the operation, specifically the movement of transformer taps and the location and sizing of reactive banks. This allows significantly reducing or delaying the investment, thus reducing its present value. The approach ensures convergence when computing the power flows and allows making an analysis of the effects of distributed generation and, if necessary, load curtailment. The model is tested on the power subtransmission network of the most important electric power distribution company in Chile, serving a city of 6 million people.
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    Stability of linear stochastic systems via Lyapunov exponents and applications to power systems
    (ELSEVIER SCIENCE INC, 2012) Verdejo, Humberto; Vargas, Luis; Kliemann, Wolfgang
    This paper studies linear systems under sustained random perturbations. The stochastic perturbation model is given by a bounded Markov diffusion process, as it appears, e. g., in the description of load or generation uncertainties of power systems. For such systems, the Lyapunov exponents describe necessary and sufficient conditions for almost sure asymptotic stability. The paper presents several numerical methods for the computation of Lyapunov exponents and applies this methodology to linear oscillators in dimension 2 and 3, and to a one machine - infinite bus electric power system. (C) 2012 Elsevier Inc. All rights reserved.