Effect of Stator D-axis Current for Tidal Current Power-Generation System using Constant Turbine-Output Control Scheme

Renewable-energy power-generation systems are garnering attention as a means to combat climate change and provide stable energy sources. The power generated by tidal currents is predictable, which offers advantages when used in conjunction with a power grid; tidal power is also unaffected by weather. This study considers a tidal current power-generation system using a doubly fed induction generator (DFIG) under variable-speed operation. Previous study has investigated the gear ratio and the capacity of the generator to produce the maximum annual energy while the system is operated at a constant turbine-output control scheme. This evaluation has been performed for considering a constant stator d-axis current of -0.93 pu. It is essential to consider the influence of the stator d-axis current. The purpose of this study is to investigate this dependence for a tidal current power-generation system using a DFIG. The capacity factor changes with a constant stator d-axis current.