Browsing by Author "Sáez, Doris"

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    Bus-Stop Control Strategies Based on Fuzzy Rules for the Operation of a Public Transport System
    (IEEE, 2012) Milla, Freddy; Sáez, Doris; Cortes, Cristián E.; Cipriano, Aldo
    In the daily operation of a bus system, the movement of vehicles is affected by uncertain conditions as the day progresses, such as traffic congestion, unexpected delays, randomness in passenger demand, irregular vehicle dispatching times, and incidents. In a real-time setting, researchers have devoted significant effort to developing flexible control strategies, depending on the specific features of public transport systems. In this paper, we propose a control scheme for the operation of a bus system running along a linear corridor, based on expert rules and fuzzy logic. The parameters of the fuzzy controllers were tuned through a particle swarm optimization (PSO) algorithm. That is, the control strategies aim at keeping regular headways between consecutive buses, with the objective of reducing the total waiting time of passengers. The proposed control systems rely on measures of the position of each bus, which are easy to obtain and implement by means of emerging automatic vehicle location devices through Global Positioning System (GPS) technology. The utilized strategies are holding, stop-skipping, and the integration of both. After tuning the controller parameters, we conducted several simulation tests, obtaining promising results in terms of savings in waiting times with the implementation of the proposed rules, noting that the best performance occurred when fuzzy rules are included. The methodology has great impact, and it is easy to implement due to its simplicity.
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    Comparison of dynamic control strategies for transit operations
    (2013) Muñoz Abogabir, Juan Carlos; Cortés, Cristián E.; Giesen Encina, Ricardo; Sáez, Doris; Delgado Breinbauer, Felipe Alberto; Valencia, Francisco; Cipriano, Aldo
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    Distributed Predictive Control Strategy for Frequency Restoration of Microgrids Considering Optimal Dispatch
    (2021) Navas F., Alex; Gómez, Juan S.; Llanos, Jacqueline; Rute, Erwin; Sáez, Doris; Sumner, Mark
    Microgrids are the cornerstone for a new model of electrical generation based on renewable resources. Commonly microgrids are controlled with a centralised hierarchical structure, which is inherited from power systems. However, a time-scale separation between traditional fast frequency restoration and slow economic dispatch may be counterproductive in the long run because the slow long-term economic dispatch increases the prediction uncertainty. In an effort to improve the economical operation of microgrids, this work proposes a distributed model predictive control strategy for the operation of isolated microgrids based on a consensus strategy that tackles both the economic dispatch and frequency restoration over the same time-scale. The proposed controller can operate without knowledge of the microgrid’s topology: instead, typical local measurements and other information from neighbouring generation units are required. Experimental results demonstrate that the controller is robust to load variations and communication issues, but the plug-and-play nature of the system is preserved.
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    Fuzzy Prediction Interval Models for Forecasting Renewable Resources and Loads in Microgrids
    (2015) Sáez, Doris; Ávila, Fernand; Olivares Quero, Daniel; Cañizares, Claudio; Marín, Luis