Abstract

Abstract
This paper presents a comparative study between a new approach for robust speed estimation in induction motor sensorless control, using a reduced order Extended Kalman Filter (EKF), and the one performed by the full order EKF. The new EKF algorithm uses a reduced order state-space model that is discretized in a particular and innovative way. In this case only the rotor flux components are estimated, besides the rotor speed, while the full order EKF also estimates stator current components. This new approach strongly reduces the execution time and simplifies the tuning of covariance matrices. The performance of speed estimation using both EKF techniques is compared with respect to computation effort, tuning of the algorithms, speed range including low speeds, load torque conditions and robustness relatively to motor parameter sensitivity.

Abstract
In the usual operation, wind park production is strongly dependent on the instantaneously available wind power. When energy storage is accessible, the wind park operation can be improved, aiming to a better exploitation of the available wind power resource. The present work proposes an optimization approach to determinate the most probable range of the output production, to be used in the definition of production profiles that will help the participation of wind power in the market. Two production profiles strategies were analyzed and compared. The forecasted wind power is represented as a stochastic variable and real wind power Portuguese conditions have been used in the evaluation of the model.

Abstract
We used a pair of Bragg gratings written in high birefringence fibre optics to measure, simultaneously, longitudinal and transverse strain and temperature. The Bragg gratings are superimposed in the same position of the fibre optic, so as to behave as a punctual sensor. The sensitivity of the spectral response of the device to longitudinal strain, transverse strain and temperature are all characterized, and the results of its application as a three-parameter sensor are also presented.

Abstract
One of the important decision problems for a power system operator is to choose the appropriate operation point when possible contingencies must be considered. The operator may decide to do nothing or to take some actions that change the operating point and decrease the negative impact (cost) of some or all the contingencies. The purpose of this paper is to investigate the applicability of utility and value functions to this decision problem, since the large range of consequences raises some doubts about the fulfillment of the theoretical conditions imposed by Decision Theory. Although not essential to this discussion, some alternatives to prescriptive methodologies are presented and discussed, mostly regarding the definition of risk attributes and other determinist equivalents, suitable for multicriteria analysis.

Abstract