Dynamic Investigation of a Double-fed Induction Generator under Faulty Operations

Although Doubly-Fed Induction Generators provide several advantages, their performance and reliability are vulnerable to electrical faults and mechanical degradation. The present study investigates the dynamic response of a 2 MW DFIG under normal and faulty conditions using a MATLAB/Simulink dq-axis model. The reference model was validated under nominal operation, accurately tracking torque, rotor speed, DC-link voltage, and rotor currents. Electrical faults were simulated by reducing stator resistance and mutual flux coupling, resulting in higher stator currents and dq-axis voltages, highlighting their sensitivity to winding faults. Mechanical degradation was studied via bearing failures, modeled as increased rotor friction and periodic torque disturbances. The prior analysis showed that higher friction reduces electromagnetic torque and q-axis currents. The periodic disturbance caused oscillations in the time domain, producing a 90 Hz spectral peak in the torque, while the stator current remained dominated by the grid frequency. These findings provide valuable insights for condition monitoring and fault diagnosis of DFIG-based systems.