I. Zubia

Treatment of L-Fuzzy contexts with absent values

This work shows how to extract the missing information from an interval-valued L-Fuzzy context with some unknown values. Absent values are replaced using implications between attributes with high levels of support and confidence. Three kinds of implications are defined and analyzed for this purpose. We apply these results to an electrical network simulation, where the estimated relations between faulty power lines and voltage measurements can be compared with their real values.

The use of linguistic variables and fuzzy propositions in the L-Fuzzy concept theory

The use of linguistic variables and fuzzy propositions in the interval-valued L-Fuzzy contexts can be an interesting tool to extract a more complete information from them. In this paper, we analyze three different situations. First, we obtain significant relations in order to study all the objects and attributes of the interval-valued L-Fuzzy context by means of the interval-valued L-Fuzzy concepts. After that, we show how to replace the erroneous values to be able to study in a suitable way the context. Finally, we use the linguistic labels to obtain a subcontext that represents our interest of study. We also show an experimental evaluation in the paper.

Design and construction of an outer-rotor PM synchronous generator for small wind turbines; comparing real results with those of FE model

The purpose of this paper is to get a contrasted flexible model in order to analyze and design an outer-rotor permanent magnet (PM) generator for directly-coupled wind turbine applications, improving the previous prototype that was designed, built and verified two years ago. A finite element analysis package program called FLUX 2D and 2D skewed has been used to design and analyze the PM generator. The 3D application was used too in order to contrast results between different applications and real results obtained in the recently built second prototype. But it should be remarked that the 3D needs a very large computer time. Anyway, all of them allow predicting inaccurate design, saving time of test bench, and that way, they make possible to rich a prototype successfully. Skewed tools have been very useful, and complemented with classic formulation adapted for the prototype, are suitable for the treatment of sloping grooves, becoming really useful the utilization of the software. Given the flexibility of the aforementioned package, its also possible the intercommunication with such a powerful tools as MATLAB-SIMULINK and others finite element packages.

An application of the L-Fuzzy Concept Theory to the short-circuit detection

There are many technical areas where we can find an application of the L-fuzzy concept theory to the knowledge extraction. Among them, one that seems of special interest is the diagnosis of failures by means of the study of an interval-valued L-fuzzy context. We will concentrate on in the electrical networks and we will construct an interval-valued L-fuzzy context that we will use, when a short-circuit is detected, to determine in what place it has occurred. It will be an alternative to the traditional method of detection of short-circuits by means of relays. In particular, the diagnosis of the short-circuits produced in the electrical network will be analysed in this paper in two different cases: in the first place we will solve the problem in the case of having all the necessary information. Next, we will see how we can obtain a diagnosis when the measurement of the voltages obtained after the short-circuit has taken place is not complete.

Dynamic Modelling of Wind Farms: A Comparative Study Between Two Modelling Approaches

World’s energy needs have encouraged the development of wind power sources. An increasing number of wind farms are being connected to the power grid and accurate the development of wind farm models need to be developed to study the dynamic behavior of them. This paper reports an investigation to compare two different modeling approaches of a real wind farm. This study is applied to the dynamic model of a real wind farm located at El Perdon, in Navarre, (Northern Spain). It consists of 30 Squirrel Cage Induction Machine (SCIM) wind generators of 660 kW and a nominal voltage of 690V. The wind farm feeds three local loads at 66 kV and is connected through two transformers to the network of 220KV.