Utilización de la herramienta Speed Court para la valoración del rendimiento en porteros de fútbol

Con el objetivo de valorar la efectividad de la técnica de desplazamiento en porteros de fútbol y la velocidad de movimiento, se realizó un estudio con 9 porteros de fútbol juveniles de alto nivel de la cantera de un equipo de la primera división española. Se ha pretendido apoyar el trabajo del cuerpo técnico. Se realizaron tres tests, un primer Test y un Re-test para validar los datos y un Post-Test para ver la evolución de los jugadores a las seis semanas. Durante esas seis semanas, un sujeto entrenó en la herramienta de valoración. El material utilizado fue la herramienta Speed-Court. Los resultados mostraron que la técnica de desplazamiento libre siempre es más eficiente en dichos tests y que los jugadores mejoraron en uno de los test tras seis semanas de entrenamiento. El jugador que entrenó durante las seis semanas mejoró todos los resultados salvo en la técnica de portero desde atrás.

Improved high-speed de-excitation system for brushless synchronous machines tested on a 20 MVA hydro-generator

Synchronous machines with brushless excitation have the disadvantage that the field winding is not accessible for the de-excitation of the machine. This means that, despite the proper operation of the protection system, the slow de-excitation time constant may produce severe damage in the event of an internal short circuit. A high-speed de-excitation system for these machines was developed, and this study presents the continuation of a previously published study. This study presents the design by computer simulation and the results of the first commissioning of this de-excitation system in a commercial 20 MVA hydro-generator. The de-excitation is achieved by inserting resistance in the field circuit, obtaining a dynamic response similar to that achieved in machines with static excitation. In this case, a non-linear discharge resistor was used, making the dynamic response even better.

Field-winding fault detection in synchronous machines with static excitation through frequency response analysis.

Frequency Response Analysis is a well-known technique for the diagnosis of power transformers. Currently, this technique is under research for its application in rotary electrical machines. This paper presents significant results on the application of Frequency Response Analysis to fault detection in field winding of synchronous machines with static excitation. First, the influence of the rotor position on the frequency response is evaluated. Secondly, some relevant test results are shown regarding ground fault and inter-turn fault detection in field windings at standstill condition. The influence of the fault resistance value is also taken into account. This paper also studies the applicability of Frequency Response Analysis in fault detection in field windings while rotating. This represents an important feature because some defects only appear with the machine rated speed. Several laboratory test results show the applicability of this fault detection technique in field windings at full speed with no excitation current.

New Fault-Resistance Estimation Algorithm for Rotor-Winding Ground-Fault Online Location in Synchronous Machines With Static Excitation

New Fault-Resistance Estimation Algorithm for Rotor-Winding Ground-Fault Online Location in Synchronous Machines With Static Excitation