Evolución y tendencias en la industria fotovoltaica española

Durante la relativamente corta vida de las instalaciones fotovoltaicas en España con relación a otro tipo de energías, la regulación efectuada en los últimos años está jugando un papel fundamental en el desarrollo de esta industria. La energía solar fotovoltaica supone actualmente el 0,1% de la demanda en barras de central (muy lejano del 10% de la energía eólica, por ejemplo), eso sí, con un incremento de número de instalaciones que se dobla cada año, y con crecimientos anuales de energía vendida totalmente exponenciales, pero que está todavía muy lejos de suponer un coste excesivo al sistema (45 millones de euros en 2006 con respecto a los 1200 millones de euros vendidos a las distribuidoras, o los 3300 millones de euros de participación en el mercado, todos ellos dentro de las energías renovables)

A fuzzy multi-criteria decision making model for construction contractor prequalification

Selecting an appropriate contractor is essential for the success of any construction project. Contractor prequalification procedure makes it possible to admit for tendering only competent contractor. Prequalification is a multi-criteria decision problem that is, in essence, largely dependent on the uncertainty and vagueness in the nature of construction projects and subjective judgement of the decision-maker. This paper presents a systematic prequalification procedure, based on Fuzzy Set Theory, whose main differences and advantages in comparison with other models are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation when pair-wise comparison judgements are used and the use of linguistic assessment or exact assessment of performance of the contractors on qualitative or quantitative criterion, respectively. Finally, a case study for the rehabilitation project of a building at Technical University of Cartagena is presented to illustrate the use of the proposed model and to demonstrate its effectiveness

A fuzzy approach to construction project risk assessment

The increasing complexity and dynamism of construction projects have imposed substantial uncertainties and subjectivities in the risk analysis process. Most of the real-world risk analysis problems contain a mixture of quantitative and qualitative data; therefore quantitative risk assessment techniques are inadequate for prioritizing risks. This article presents a risk assessment methodology based on the Fuzzy Sets Theory, which is an effective tool to deal with subjective judgement, and on the Analytic Hierarchy Process (AHP), which is used to structure a large number of risks. The proposed methodology incorporates knowledge and experience acquired from many experts, since they carry out the risks identification and their structuring, and also the subjective judgements of the parameters which are considered to assess the overall risk factor: risk impact, risk probability and risk discrimination. All of these factors are expressed by qualitative scales which are defined by trapezoidal fuzzy numbers to capture the vagueness in the linguistic variables. The most notable differences with other fuzzy risk assessment methods are the use of an algorithm to handle the inconsistencies in the fuzzy preference relation when pair-wise comparison judgements are necessary, and the use of trapezoidal fuzzy numbers until the defuzzification step. An illustrative example on risk assessment of a rehabilitation project of a building is used to demonstrate the proposed methodology

Last planner control system applied to a chemical plant construction

The main difference between the Last Planner production control system developed by Ballard and classical control systems is the way in which projects are controlled and planned. The Last Planner system focuses on controlling production units, workflows and the quality of the performed work. It also permits the identification of the causes for the non-completion of planned work and decision making in accordance with the project requirements so that actions are timely and productivity is increased. The objective of this paper is to present the results obtained from implementing the Last Planner system in the construction department of a chemical company. In this department, an information flow problem was detected among its members, in which supervisors lacked knowledge about the work to be performed until the project had been perfectly designed. This problem often led to meant long delays in the projects. The results from Last Planner system implementation show that identifying the constraints of the planned work leads to an improvement in the percentage and quality of completed activitie

Towards an overall simulator for a synchronous wind energy system

The amount of electrical energy obtained from renewable sources, specially wind energy, is rising quickly. The interface of this distributed generation with the electrical network will have soon an important influence on control, power quality and voltage stability issues of the whole energy net. In order to be prepared to that change it is necessary to simulate, with a sensible accuracy, the transient events, which happen during normal operation or during faults, and have influence in either net or inner variables. So in this way, it is important to model a wind energy system, taking into account every subsystem that have a significant influence over the transient behavior of the compound system. Some important and recent papers are oriented to analyze the stability [1] and the power quality of the wind systems [2]. In the first one, a doubly fed generator is analyzed from an electrical stability point of view; and in the second one the RMS values of the main electrical variables have been simulated in an overall wind energy system. An interesting paper describing the transient problems in relation with the grid integration of wind turbines can be seen in [3]. In this paper, as a preliminary design of an overall simulator, a variable speed system with a wound rotor synchronous generator is analyzed and a connection of the windmill with a variable wind is simulated.The authors are thankful to the support from the Caja de Ahorros del Mediterraneo (BECA-CAM predoctoral 2003, a grant conceded to the first author). This research is partially supported by the Consejeria de Educación y Ciencia de la Comunidad Autónoma de la Región de Murcia (Project Séneca 2002: PC-MC/3/00074/FS/02)

Real time test benchmark design for photovoltaic grid connected control systems

This paper presents a dual digital signal processor (DSP) hardware architecture for a grid-connected photovoltaic interface test benchmark, based on a cascade DC/DC converter and DC/AC inverter, with coordinated control algorithms. The control hardware has been designed to test distributed generation (DG) interfaces to be integrated in a hierarchical structure of computational agents, to apply distributed control techniques to the power system management. The proposed dual DSP architecture enables the programming of the control software for the DC/DC converter and the DC/AC inverter in the same processor, to keep the other one for additional operations that are required when there is a high degree of interaction between the DG unit and the rest of the electrical grid components. The hardware architecture has been tested in several real situations such as power factor correction and anti-islanding protection

Revisión de los algoritmos anti-isla: problemática asociada a la generación distribuida

Este documento realiza una revisión de los algoritmos más usados actualmente para la detección del fenómeno de "isla", un fenómeno eléctrico que se produce cuando una fuente de continúa energizando una parte de la red después de que dicha porción de red haya sido interrumpida o desconectada por diversas causas. A lo largo del artículo se establece la distinción entre los dos tipos de métodos existentes: pasivos (basados en la monitorización de determinados parámetros como tensión y frecuencia) y activos (introducen perturbaciones en el circuito y monitorizan la respuesta). Se analizan también las principales ventajas e incovenientes de cada método y a modo de conclusión se recomienda el más adecuado.Asociación de Jóvenes Investigadores de Cartagena, (AJICT). Universidad Politécnica de Cartagena. Escuela Técnica Superior de Ingeniería Industrial UPCT, (ETSII). Escuela Técnica Superior de Ingeniería Agronómica, (ETSIA), Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT). Cátedra Bancaja Jóvenes Emprendedores. Hero. Parque Tecnológico de Fuente Álamo. Grupo Aquiline