Input variable selection for forecasting models

2002 IFAC15th Triennial World Congress, Barcelona, SpainThe selection of input variables plays a crucial role when modelling time series. For nonlinear models there are not well developed techniques such as AIC and other criteria that work with linear models. In the case of Short Term Load Forecasting (STLF) generalization is greatly influenced by such selection. In this paper two approaches are compared using real data from a Spanish utility company. The models used are neural networks although the algorithms can be used with other nonlinear models. The experiments show that that input variable selection affects the performance of forecasting models and thus should be treated as a generalization problem

A new concept of invariance for saturated systems

In this paper, a new concept of invariance for saturated linear systems is presented. This new notion of invariance, denoted SNS-invariance, has a number of geometrical properties that makes its use suitable for the estimation of the domain of attraction of saturated systems. The notion of SNS-domain of attraction, that serves as an estimation of the domain of attraction of a saturated system, is introduced. It is shown that, in case of single input saturated systems, any contractive set is contained in the SNS-domain of attraction. A simple algorithm that converges to the SNS-domain of attraction is presented. Some illustrative examples are given

Gestión e implementación de una pasarela HTTP-OPC aplicado a una planta solar

XXVI Jornadas de Automática, Alicante-Elche, 2005El propósito de este artículo es detallar cómo conseguir un acceso eficiente a datos provenientes de un dispositivo genérico o planta industrial situada dentro de una red local. Dicho dispositivo debe estar conectado a un servidor OPC que permita acceder a las distintas variables. La situación que se intenta resolver es aquella en la que solamente es posible acceder a las variables de un dispositivo cualquiera desde un equipo que esté necesariamente situado dentro de la misma red local. La solución abordada en este artículo se basa en la elaboración de una aplicación web que permita proporcionar el acceso a distintos usuarios tanto desde dentro como desde fuera de la red a la que pertenezca la planta. Esta solución permite también el control remoto ya sea de una planta industrial o cualquier otro tipo de dispositivo haciendo uso de OPC. En concreto, se mostrar´a una Planta Solar sobre la que se explicar´an los aspectos de implementación