Improvement of DFIG low voltage Ride-through capability based On Grid Code Requirements

Now a day’s wind systems have became a fully commercial and inevitable process among renewable energy sources. The main issue in relation to wind turbines equipped with doubly-fed induction generators (DFIG) is the low voltage Ride-through capability (LVRT) in the event of fault or sudden voltage drop along with the grid code. DFIG is very sensitive to disturbances, due to the direct connection of the stator to the grid. When fault or sudden voltage changes occur, the variation in the stator transient flux leads to an increase in the rotor current and the DC link voltage. Considering that the DFIG convertors possess the 20% to 30% of nominal power of generator, this surplus current hurts the DFIG and cut it out of the circuit. Therefore the failure in the rotor circuit and its converter and cutting the generator out of the grid should be prevented by applying some methods. A common technique to avoid damage of the converter is using the crowbar protection. By this circuit, during fault time the generator can remain in the grid. But DFIG control on the speed and reactive power at the presence of the crowbar in the circuit is interrupting. In this paper, fault current limiters are used in order to improve the voltage recovery and uninterrupted operation of DFIG with its ability to maintain controllable during the fault time. The results of simulations with MATLAB / Simulink show an improvement in the DFIG performance based on proposed method during the fault time.

کلیدواژه ها:

Doubly-Fed Induction Generators (DFIG) ، Low Voltage Ride-Through (LVRT) ، Wind Turbine (WT) ، Grid Code ، Superconductor Fault Current Limiters (SFCL) ،