DIAS, R. A.; http://lattes.cnpq.br/5387063970690504; DIAS, Ramon Araújo.
Resumo:
This work evaluates power quality and energy efficiency in wind farms. The main focus
is the analysis of the skin effect caused by harmonics in the cables of real wind farm
installation. Data presented in the study of power quality performed to obtain access to
the electric system operator, was used for the development of this research. The
software HarmZs, commonly used in power quality studies, was used to obtain the
harmonic distortion values for currents measured at wind farm site. The wind farm
presented problems in the power quality delivered at the point of common connection to
the national electrical power system. The additional losses calculations for the wind
farm internal system presented an increase of up to 8% caused by the harmonic currents
in the installation of the wind farm. With the aid of the software COMSOL
Multiphysics®, the current density distributions from the harmonic currents in the
cables were evaluated. The cables used for this study are implemented in the connection
between wind turbine and elevator transformer. These cables present greater harmonic
current distortions. It has been found that adjacent cables interfere with current density
distribution and that the current density increase at cable end can reach 68% when
compared to the case where there is no interference from adjacent cables. Finally, the
thermal analysis in the cables indicated an elevated temperature, 136oC, for the
conductors of phase B. The increase of temperature observed can be mainly attributed to
the losses due to the fundamental component current and the process of thermal
conduction between phases.