A Multiple Criteria Utility-based Approa h for the Unit Commitment with Wind Power and Pumped Storage Hydro

The integration of wind power in eletricity generation brings new challenges to unit commitment due to the random nature of wind speed. For this particular optimisation problem, wind uncertainty has been handled in practice by means of conservative stochastic scenario-based optimisation models, or through additional operating reserve settings. However, generation companies may have different attitudes towards operating costs, load curtailment, or waste of wind energy, when considering the risk caused by wind power variability. Therefore, alternative and possibly more adequate approaches should be explored. This work is divided in two main parts. Firstly we survey the main formulations presented in the literature for the integration of wind power in the unit commitment problem (UCP) and present an alternative model for the wind-thermal unit commitment. We make use of the utility theory concepts to develop a multi-criteria stochastic model. The objectives considered are the minimisation of costs, load curtailment and waste of wind energy. Those are represented by individual utility functions and aggregated in a single additive utility function. This last function is adequately linearised leading to a mixed-integer linear program (MILP) model that can be tackled by general-purpose solvers in order to find the most preferred solution. In the second part we discuss the integration of pumped-storage hydro (PSH) units in the UCP with large wind penetration. Those units can provide extra flexibility by using wind energy to pump and store water in the form of potential energy that can be generated after during peak load periods. PSH units are added to the first model, yielding a MILP model with wind-hydro-thermal coordination. Results showed that the proposed methodology is able to reflect the risk profiles of decision makers for both models. By including PSH units, the results are significantly improved.

Manipulator trajectory planning using a MOEA

Generating manipulator trajectories considering multiple objectives and obstacle avoidance is a non-trivial optimization problem. In this paper a multi-objective genetic algorithm based technique is proposed to address this problem. Multiple criteria are optimized considering up to five simultaneous objectives. Simulation results are presented for robots with two and three degrees of freedom, considering two and five objectives optimization. A subsequent analysis of the spread and solutions distribution along the converged non-dominated Pareto front is carried out, in terms of the achieved diversity.

Serviço de revisão bibliográfica colaborativa

The investigation communities spread all over the planet create considerable amounts of knowledge while developing their activities. The most known way of communicating this knowledge is through papers publishing, books and reports, among others. These documents are stored in libraries and even more nowadays, in the Internet, allowing people to access up dated information more efficiently than ever. However, this great amount of available information can represent an obstacle to its transformation in knowledge. It is therefore relevant the implementation of mechanisms that enable this transformation. In this dissertation a proposal for creation of a new information service is presented. It concerns a service of collaborative bibliographic revision, which supports the investigators in this specific task as well as in registering its results, thus providing future revisions by third party. The developed model takes its grounds in a documental background accessible through a commercial libraries management system, under which a "web" of semantically enriched connections is established and that register preferential paths for exploring this background, according to multiple criteria as well as notes to documents and paths themselves. A prototype is presented it implements the fundamental ideas of the model, which at its basic level represents an access interface to a repository of documents in electronic form. Based on this level there are two others, focussed on the registration of information added by the users of the service. The results emerged from this prototype clearly show the viability of the model.