Automatic Synthesis of Feedforward Elements in Quantitative Feedback Theory

Recent developments in quantitative feedback theory (QFT) lead to feedforward design problems with both magnitude and phase constraints. In these cases, manual feedforward tuning becomes much more challenging and time consuming than the traditional prefilter shaping taking place on the Bode plot. This article presents a general procedure for the automatic synthesis of such elements. Feedforward bounds in the complex plane are expressed as constraints of a linear programming problem in which the Bode real-complex relation is implicitly considered, ensuring a stable rational solution. The methodology is successfully tested in a well-known benchmark problem.Euskal Herriko Unibertsitatea, Grant/Award Number: GIU16/54; Ministerio de Economia y Competitividad, Grant/Award Number: DPI2015-64985-

Operating Point Optimization of a Hydrogen Fueled Hybrid Solid Oxide Fuel Cell-Steam Turbine (SOFC-ST) Plant

This paper presents a hydrogen powered hybrid solid oxide fuel cell-steam turbine (SOFC-ST) system and studies its optimal operating conditions. This type of installation can be very appropriate to complement the intermittent generation of renewable energies, such as wind generation. A dynamic model of an alternative hybrid SOFC-ST configuration that is especially suited to work with hydrogen is developed. The proposed system recuperates the waste heat of the high temperature fuel cell, to feed a bottoming cycle (BC) based on a steam turbine (ST). In order to optimize the behavior and performance of the system, a two-level control structure is proposed. Two controllers have been implemented for the stack temperature and fuel utilization factor. An upper supervisor generates optimal set-points in order to reach a maximal hydrogen efficiency. The simulation results obtained show that the proposed system allows one to reach high efficiencies at rated power levels.This work has been carried out in the Intelligent Systems and Energy research group of the University of the Basque Country (UPV/EHU) and has been supported by the UFI11/28 research grant of the UPV/EHU and by the IT677-13 research grant of the Basque Government (Spain) and by DPI2012-37363-CO2-01 research grant of the Spanish Ministry of Economy and Competitiveness