Showing papers by "Vicente Feliu-Batlle published in 2014"

Mathematical model for robust control of an irrigation main canal pool

Abstract: This paper describes the formulation and development of a mathematical model for high-performance robust controller design techniques, based on a complete identification for control procedure, of an irrigation main canal pool (true plant), which is characterized by the exhibition of large variations in its dynamic parameters when the discharge regime changes in the operating range Qmin, Qmax]. Real-time field data has been used. Four basic steps of the proposed procedure have been defined in which all the stages, from the design of the experiments to the model validation, are considered. This procedure not only delivers a nominal model of the true plant, but also a reliable estimate of its model uncertainty region bounded by the true plant models under minimum and maximum operating discharge regimes (limit operating models). The model uncertainty set, defined by the nominal model and its uncertainty region, is characterized by its being as tight as possible to the true irrigation main canal pool. The obtained results are very promising since this kind of models facilitates the design of robust controllers, which allow improving the operability of irrigation main canal pools and also substantially reduce water losses. A mathematical model for robust control of an irrigation canal pool has been developed.A nominal model of the plant and its explicit uncertainty region have been estimated.The model uncertainty set of the plant has been delivered.Based on the obtained model an H∞ robust controller has been designed.

Control Robusto de Orden Fraccionario de la Presión del Vapor en el Domo Superior de una Caldera Bagacera

Abstract: This paper presents a fractional order controller of the class IDα-1 for robust control of the steam pressure in the steam drum of a bagasse boiler. The proposed controller improves the effectiveness on the control, and likewise the energy efficiency of this plant. The dynamics of this process drastically changes with the variation of the specific heat of combustion (I) and the use of a fractional order control looks therefore suitable. A mathematical nominal model of the steam pressure variation in the steam drum of a bagasse boiler was obtained and validated. Experimental studies provided an estimation of the range of variation of the parameters’ model when the specific heat of combustion varies in the operating range [Imin, Imax]. The proposed fractional order controller has been compared to the standard PI and PID controllers. All of them have been designed by means of the same frequency specifications and their nominal time responses are similar when input reference changes and in presence of disturbances. The PID controller and the fractional order one have been also designed in order to maximize their robustness when the gain of the steam pressure in the steam drum of bagasse boiler changes in the range [Kmin, Kmax]. Simulated results show that the fractional order controller is more robust than the PI and the PID controllers when the gain of the plant changes but preserving the robustness when time delay varies.

Robust fractional-order temperature control of a steel slab reheating furnace with large time delay uncertainty

Abstract: This paper proposes a new strategy to control the temperature of a steel slab reheating furnace based on fractional-order controllers. A second order plus time delay model of the preheating zone of this process is used, which was obtained from an identification procedure applied in an industrial furnace. It is shown that this process experiences very large time delay changes. A fractional-order integral controller (FI) combined with a Smith predictor is designed, which is robust to changes in such time delay. Simulated results of a standard PID controller, PI controller combined with a Smith predictor and the proposed FI controller also combined with a Smith predictor are compared. Seven performance indexes have been used in this comparison: four related to the output performance (settling time, overshoot, ISE and IAE), and three related to the control signal (maximum amplitude, control effort TV and fuel consumption). The analysis of these indexes show that the fractional-order controller exhibits the most robust behaviour (lowest indexes averaged in all the range of time delay variation) for ranges that include large time delays. Then the robustness features of the FI controller combined with a Smith predictor outperform the other integer order controllers both in the time response to a setpoint change and in the control effort aspects.