What are Double Fed Induction Generators (DFIG)?
DFIG stands for Double Fed Induction Generators. They are most noticeably used in wind turbines for electricity production. Unlike a generator alternator, which generates electricity rotating at a nice constant 1500RPM. The wind is significantly less reliable. Maximise the amount of energy with DFIG. Consequently, this allows electricity generation from much lower rotational speeds.
Advantages of using DFIG
Advantages of using DFIG- Reduced inverter cost, because inverter rating is typically 25% of total system power, while the speed range of the ASG is ±33% around the synchronous speed.
- Secondly, reduced cost of the inverter filters and EMI filters. Filters rated for 0.25 p.u. total system power. Inverter harmonics represent a smaller fraction of total system harmonics.
- Above all, improved system efficiency. Approximately 2-3% obtained.
- Power-factor control likely implemented at lower costs. The DFIG system (four-quadrant converter and induction machine) operates similar to a synchronous generator. The converter has to provide only excitation energy.
