Open AccessOvercurrent estimation in a doubly‐fed induction generator‐DC system during a voltage dip in the dc grid
Author(s) -
Marques Gil,
Iacchetti Matteo
Publication year - 2016
Publication title -
iet renewable power generation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.005
H-Index - 76
eISSN - 1752-1424
pISSN - 1752-1416
DOI - 10.1049/iet-rpg.2015.0509
Subject(s) - overvoltage , control theory (sociology) , stator , voltage , rotor (electric) , overcurrent , induction generator , generator (circuit theory) , electrical engineering , engineering , physics , computer science , power (physics) , control (management) , quantum mechanics , artificial intelligence
This study analyses the voltage dip behaviour of the doubly‐fed induction generator (DFIG) connected to a common dc link on both the stator and rotor sides, via a diode bridge and a voltage source inverter (VSI), respectively. After a voltage dip in the dc grid, the rotor VSI can transiently lose control so that rotor currents circulate through the VSI free‐wheeling diodes. However, during the uncontrolled period, both stator and rotor voltages are clamped to the same dc‐link voltage and no rotor overvoltage occurs. In order to analyse the behaviour of the system during the first periods of the uncontrolled current transients, this study presents a simplified average model which is validated through simulations. Voltage dips are classified into three types depending on their severity. A simple analytical expression is derived for the maximum amplitude of the current during the voltage dip, and an overcurrent chart in the plane ‘rotor speed – dip amplitude’ is deduced. These results provide deep insight into the DFIG‐DC system behaviour and are useful for design purpose.