Browsing by Author "Navarro Espinosa, Alejandro"

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    Importance of hourly multi-bus unit commitment models in the context of high adoption of variable renewable energies: A chilean example
    (IEEE, 2017) Ávila, Fernanda; Navarro Espinosa, Alejandro; Ayala, Javier; Córdova, Samuel; Cerda Vasquez, Pablo Eduardo; Rudnick Van de Wyngard, Hugh
    The increasing levels of Variable Renewable Energies (VRE) require additional levels of flexibility in present power systems due to their intermittency and the resulting needs of reserve for increasing/reducing the generation with enough speed to maintain the system balance. In this context, the traditional long-term hydrothermal optimal dispatch models are not sufficient to adequately represent this situation, particularly in systems with hydro reservoirs that can store water from one period to another. These models do not use sequential representation of time periods (on the contrary, they work with load blocks) and they do not incorporate most of the non-linear constraints to model specific characteristics such as: minimum power, ramp up/down rates, stabilization times, minimum time in service, minimum down-time, etc. Therefore, more detailed models must be used to comprehensively represent the impact of VRE in the system operation. To assess the true cost of power system operation with high adoption of VRE, this work develops a detailed multi-bus hourly unit commitment model with all non-linear constraints, showing the importance of this type of model for assessing cycling and start-up in the new VRE paradigm.
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    Improving power system reliability through optimization via simulation
    (IEEE, 2017) Sacaan, Rafael; Rudnick Van de Wyngard, Hugh; Lagos, Tomás; Ordóñez, Fernando; Navarro Espinosa, Alejandro; Moreno, Rodrigo
    Due to the stochastic nature of equipment failures, the accurate assessment of power system reliability is a complex task. Consequently, the optimal selection of new network infrastructure to improve reliability is even harder. In this paper, an optimization via simulation approach is proposed to find the optimal set of network assets to improve system reliability. Particularly, an Industrial Strength COMPASS algorithm is implemented to find the optimal set of new transmission lines that maximizes system reliability subject to a budget constraint. This algorithm iteratively proposes, in a first stage, a set of new transmission lines that are then tested, in a second stage, via simulation of the system operation, including impact of various network failures. In the second stage, the sequence day-ahead unit commitment plus real-time operation is modeled along with a sequential Monte Carlo simulation to determine highly detailed system operation under network outages and thus calculate the associated expected energy not supplied.