Artículos iAMhttp://hdl.handle.net/10259/42692024-03-29T09:47:41Z2024-03-29T09:47:41ZFeasibility of a Simple Small Wind Turbine with Variable-Speed Regulation Made of Commercial ComponentsBravo Cuesta, AndrésGómez Gil, Francisco JavierMartín Fraile, Juan VicenteAusín Rodríguez, JesúsRuiz Calvo, JustoPeláez Vara, Jesúshttp://hdl.handle.net/10259/43752022-12-19T12:19:58Z2013-07-01T00:00:00ZFeasibility of a Simple Small Wind Turbine with Variable-Speed Regulation Made of Commercial Components
Bravo Cuesta, Andrés; Gómez Gil, Francisco Javier; Martín Fraile, Juan Vicente; Ausín Rodríguez, Jesús; Ruiz Calvo, Justo; Peláez Vara, Jesús
The aim of this study was to propose and evaluate a very small wind turbine
(VSWT) that competes with commercial grid-connected VSWTs in terms of simplicity,
robustness and price. Its main components are a squirrel-cage induction generator (SCIG)
driven by a frequency converter. The system has a direct-drive shaft, and may be
constructed with commercial equipment. Simulation of the wind turbine effect is done with
a motor. A control program regulates the variable-speed of rotation through three
operational modes: (i) to drive the turbine to its optimum operation point; (ii) to limit its
maximum rotational speed; and (iii) to limit the maximum power it generates. Two tests
were performed, in order to evaluate the dynamic response of this system under variable
wind speeds. The tests demonstrate that the system operates at the optimum operational
point of the turbine, and within the set limits of maximum rotational speed and maximum
generated power. The drop in performance in relation to its nominal value is about 75%,
when operating at 50% of the nominal power. In summary, this VSWT with its proposed
control program is feasible and reliable for operating direct-shaft grid-connected VSWTs.
2013-07-01T00:00:00ZAnalysis and Prediction of Energy Production in Concentrating Photovoltaic (CPV) InstallationsGómez Gil, Francisco JavierXiaoting, WangBarnett, Allenhttp://hdl.handle.net/10259/43742021-11-10T09:38:22Z2012-03-01T00:00:00ZAnalysis and Prediction of Energy Production in Concentrating Photovoltaic (CPV) Installations
Gómez Gil, Francisco Javier; Xiaoting, Wang; Barnett, Allen
A method for the prediction of Energy Production (EP) in Concentrating
Photovoltaic (CPV) installations is examined in this study. It presents a new method that
predicts EP by using Global Horizontal Irradiation (GHI) and the Photovoltaic
Geographical Information System (PVGIS) database, instead of Direct Normal Irradiation
(DNI) data, which are rarely recorded at most locations. EP at four Spanish CPV
installations is analyzed: two are based on silicon solar cells and the other two on
multi-junction III-V solar cells. The real EP is compared with the predicted EP. Two
methods for EP prediction are presented. In the first preliminary method, a monthly
Performance Ratio (PR) is used as an arbitrary constant value (75%) and an estimation of
the DNI. The DNI estimation is obtained from GHI measurements and the PVGIS
database. In the second method, a lineal model is proposed for the first time in this paper to
obtain the predicted EP from the estimated DNI. This lineal model is the regression line
that correlates the real monthly EP and the estimated DNI in 2009. This new method
implies that the monthly PR is variable. Using the new method, the difference between the
predicted and the real EP values is less than 2% for the annual EP and is in the range of
5.6%–16.1% for the monthly EP. The method that uses the variable monthly PR allows the
prediction of the EP with reasonable accuracy. It is therefore possible to predict the CPV
EP for any location, using only widely available GHI data and the PVGIS database.
2012-03-01T00:00:00ZA Kalman Filter Implementation for Precision Improvement in Low-Cost GPS Positioning of TractorsGómez Gil, JaimeRuiz González, RubénAlonso Garcia, SergioGómez Gil, Francisco Javierhttp://hdl.handle.net/10259/43732021-11-10T09:38:22Z2013-11-01T00:00:00ZA Kalman Filter Implementation for Precision Improvement in Low-Cost GPS Positioning of Tractors
Gómez Gil, Jaime; Ruiz González, Rubén; Alonso Garcia, Sergio; Gómez Gil, Francisco Javier
Low-cost GPS receivers provide geodetic positioning information using the
NMEA protocol, usually with eight digits for latitude and nine digits for longitude. When
these geodetic coordinates are converted into Cartesian coordinates, the positions fit in a
quantization grid of some decimeters in size, the dimensions of which vary depending on
the point of the terrestrial surface. The aim of this study is to reduce the quantization errors
of some low-cost GPS receivers by using a Kalman filter. Kinematic tractor model
equations were employed to particularize the filter, which was tuned by applying Monte
Carlo techniques to eighteen straight trajectories, to select the covariance matrices that
produced the lowest Root Mean Square Error in these trajectories. Filter performance was
tested by using straight tractor paths, which were either simulated or real trajectories
acquired by a GPS receiver. The results show that the filter can reduce the quantization
error in distance by around 43%. Moreover, it reduces the standard deviation of the heading
by 75%. Data suggest that the proposed filter can satisfactorily preprocess the low-cost GPS
receiver data when used in an assistance guidance GPS system for tractors. It could also be
useful to smooth tractor GPS trajectories that are sharpened when the tractor moves over
rough terrain.
2013-11-01T00:00:00ZThe Influence of Tractor-Seat Height above the Ground on Lateral VibrationsGómez Gil, JaimeGómez Gil, Francisco JavierMartín de León, Rebecahttp://hdl.handle.net/10259/43722021-11-10T09:38:22Z2014-10-01T00:00:00ZThe Influence of Tractor-Seat Height above the Ground on Lateral Vibrations
Gómez Gil, Jaime; Gómez Gil, Francisco Javier; Martín de León, Rebeca
Farmers experience whole-body vibrations when they drive tractors. Among the
various factors that influence the vibrations to which the driver is exposed are terrain
roughness, tractor speed, tire type and pressure, rear axle width, and tractor seat height
above the ground. In this paper the influence of tractor seat height above the ground on the
lateral vibrations to which the tractor driver is exposed is studied by means of a
geometrical and an experimental analysis. Both analyses show that: (i) lateral vibrations
experienced by a tractor driver increase linearly with tractor-seat height above the ground;
(ii) lateral vibrations to which the tractor driver is exposed can equal or exceed vertical
vibrations; (iii) in medium-size tractors, a feasible 30 cm reduction in the height of the
tractor seat, which represents only 15% of its current height, will reduce the lateral
vibrations by around 20%; and (iv) vertical vibrations are scarcely influenced by
tractor-seat height above the ground. The results suggest that manufacturers could increase
the comfort of tractors by lowering tractor-seat height above the ground, which will reduce
lateral vibrations.
2014-10-01T00:00:00Z