access icon free Comparison of rotor electrical fault indices owing to inter-turn short circuit and unbalanced resistance in doubly-fed induction generator

Doubly-fed induction generator (DFIG) is the dominant technology in the wind energy market. Rotor inter-turn short-circuits (RITSCs) and unbalanced rotor resistance (URR) are the main types of rotor electrical asymmetries in DFIG. The URR has already been considered as an electrical fault or asymmetry in the rotor of DFIG. Although the RITSC introduces URR into the rotor circuit its consequences are not similar due to the structure of the machine and presence of current controllers in the DFIG system. In this study, both RITSC and URR are proposed and compared, and the detection of these faults was performed using appropriate indices in the stator current, reactive power, and rotor modulating voltage signals, which are available in the control system of the DFIG. Furthermore, it is supposed that the discrimination between these two types of faults is feasible by utilising proper fault indices at various operating regions of the wind turbine. The performance of the defined fault indices, for different fault severities, is verified using an experimental setup with the DFIG operating under several conditions such as different power injection into the grid and different rotor speeds, including sub-synchronous and super-synchronous operation.

Inspec keywords: wind turbines; rotors; fault diagnosis; stators; wind power plants; asynchronous generators

Other keywords: rotor electrical fault indices; proper fault indices; rotor circuit its consequences; defined fault indices; unbalanced resistance; wind energy market; DFIG system; URR; rotor electrical asymmetries; different rotor speeds; DFIG operating; rotor modulating voltage signals; reactive power; RITSC; doubly-fed induction generator; different fault severities; unbalanced rotor resistance; short circuit

Subjects: Control of electric power systems; Wind power plants; Asynchronous machines

http://iet.metastore.ingenta.com/content/journals/10.1049/iet-epa.2018.5528
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