1,899 research outputs found

    Seasonal Analysis of Economic Time Series

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    Demand and Storage Management in a Prosumer Nanogrid Based on Energy Forecasting

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    Energy efficiency and consumers' role in the energy system are among the strategic research topics in power systems these days. Smart grids (SG) and, specifically, microgrids, are key tools for these purposes. This paper presents a three-stage strategy for energy management in a prosumer nanogrid. Firstly, energy monitoring is performed and time-space compression is applied as a tool for forecasting energy resources and power quality (PQ) indices; secondly, demand is managed, taking advantage of smart appliances (SA) to reduce the electricity bill; finally, energy storage systems (ESS) are also managed to better match the forecasted generation of each prosumer. Results show how these strategies can be coordinated to contribute to energy management in the prosumer nanogrid. A simulation test is included, which proves how effectively the prosumers' power converters track the power setpoints obtained from the proposed strategy.Spanish Agencia Estatal de Investigacion ; Fondo Europeo de Desarrollo Regional

    Recursive Estimation in Econometrics

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    An account is given of recursive regression and of Kalman filtering which gathers the important results and the ideas that lie behind them within a small compass. It emphasises the areas in which econometricians have made contributions, which include the methods for handling the initial-value problem associated with nonstationary processes and the algorithms of fixed-interval smoothing.Recursive regression, Kalman filtering, Fixed-interval smoothing, The initial-value problem

    Forecast Combination

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    Actualmente existen diversas metodologías de pronóstico, que van desde el conocimiento empírico hasta métodos innovadores, individuales o combinados, que demuestran resultados óptimos. Este documento se deriva de un proceso de investigación y presenta alternativas relacionadas con las combinaciones de pronósticos, utilizando metaheurísticas, por ejemplo, mediante la búsqueda tabú y la programación evolutiva para optimizar el pronóstico. El documento presenta pronósticos combinados basados en la programación evolutiva utilizando mezclas de modelos de regresión bayesiana y modelos de regresión lineal clásico, el modelo de media móvil integrado autorregresivo, el suavizado exponencial y la regresión bayesiana. El documento presenta dos artículos derivados de investigación, la primera compara el algoritmo combinado con los resultados individuales de estos modelos individuales y con la combinación de Bates y Granger utilizando un indicador de error y el valor simétrico de error absoluto medio. Esos modelos y la combinación se aplicaron a la simulación de series temporales y a un caso real de ventas de productos lácteos, generando así pronósticos combinados multiproductos tanto para la simulación como para el caso real. La nueva combinación combinada con la metaheurística evolutiva mostró mejores resultados que los de los otros que se utilizaron. La segunda investigación utiliza series de tiempo simuladas, diseñando dos metaheurísticas basadas en la lista Tabú, que aprenden de los datos con base en el comportamiento estadístico de éstos, como el cluster, así como del mismo valor optimizado del error de ajuste, y se comparan las combinaciones de pronósticos con resultados de modelos individuales a tres tipos de series de tiempo.Currently diverse forecasting methodologies exists, going from the empirical knowledge to the innovative methods, individual or combined, demonstrating optimal results. This document is derived from a research process, and presents alternatives related to forecast combinations, using metaheuristics, for example, by using Tabu search and Evolutive programing to optimize forecasting. One of the designed process consists of creating combination forecasts based on evolutionary programming using, first, a mixture of Bayesian regression models and, second, a mixture of the classical linear regression model, the autoregressive integrated moving average model, exponential smoothing and Bayesian regression. The first research compares the novel combined algorithm with the individual results of these individual models and with the Bates and Granger combination using an error indicator and the symmetrical mean absolute error value. Those models and the novel design were applied to time series simulation and to a real case of dairy products sales, thus generating multiproduct combination forecasts for both the simulation and the real case. The novel combination combined with the evolutionary metaheuristic showed better results than those of the others that were used. The second research uses simulated time series and other metaheuristic that learns from the data an statistical behavior.Tecnológico de Antioquia, Universidad Nacional de Colombia.Doctorad

    Grey double exponential smoothing model and its application on pig price forecasting

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    The file attached to this record is the authors final peer reviewed version. The version of record can be found by following the DOI link.To resolve the conflict between our desire for a good smoothing effect and desire to give additional weight to the recent change, a grey accumulating generation operator that can smooth the random interference of data is introduced into the double exponential smoothing method. The results of practical numerical examples have demonstrated that the proposed grey double exponential smoothing method outperforms the traditional double exponential smoothing method in forecasting problems

    A penalized framework for distributed lag non-linear models.

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    : Distributed lag non-linear models (DLNMs) are a modelling tool for describing potentially non-linear and delayed dependencies. Here, we illustrate an extension of the DLNM framework through the use of penalized splines within generalized additive models (GAM). This extension offers built-in model selection procedures and the possibility of accommodating assumptions on the shape of the lag structure through specific penalties. In addition, this framework includes, as special cases, simpler models previously proposed for linear relationships (DLMs). Alternative versions of penalized DLNMs are compared with each other and with the standard unpenalized version in a simulation study. Results show that this penalized extension to the DLNM class provides greater flexibility and improved inferential properties. The framework exploits recent theoretical developments of GAMs and is implemented using efficient routines within freely available software. Real-data applications are illustrated through two reproducible examples in time series and survival analysis.<br/
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