Fault detection of fault ride through for doubly-fed induction generator based wind energy systems

Fault detection and mitigation is of high importance for existing DFIG based wind energy conversion systems. Keeping the doubly-fed induction generator (DFIG) online during faults is desirable since reconnection can cause system instability. Grid disturbances induce large rotor currents at the machine side power electronic converter. The currents exceed the device ratings potentially causing damage. A stand alone active crowbar protection system is proposed in this project where the active crowbar is connected to the rotor windings providing a bypass path for the excessive current to dissipate across. The fault detection algorithm are developed using negative sequence detection method, which detected the negative sequence instantaneous power. The protecion system disconnects the converter from the system while activating crowbar for providing fault current circulation. The overall wind energy system with active crowbar was modelling in Matlab/Simulink and simulation results verify the functionality of the proposed protection system.